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									1    SHAFTS (English Units, with Optional Provisions)

2    NOTE: These Bridge Special Provisions are subject to change. Contact Mike
3    Bauer in the WSDOT Bridge Office at 360-705-7190 or bauerm@wsdot.wa.gov,
4    or Mohammad Sheikhizadeh in the WSDOT Construction Office at 360-705-
5    7828 or sheikhm@wsdot.wa.gov for the latest version of these special
6    provisions.

 7   A meeting shall be held early in the shaft design process to discuss the casing
 8   placement construction requirements appropriate for the geotechnical and
 9   general site conditions. For WSDOT projects, those involved should include
10   the Bridge and Structures Office, Materials Laboratory Geotechnical Services
11   Branch, Construction Office, and representation from ADSC and other
12   appropriate design and geotechnical consultants assigned to the project. For
13   Local Agency non-WSDOT projects, those involved should include appropriate
14   design and geotechnical designers and consultants assigned to the project,
15   and representation from ADSC. Arrangements for ADSC representation at
16   such discussions or meetings should be made through Alan Macnab at (206)
17   575-8248.
18   Description
19   1.01 Shafts
20
21       A.   This item of work shall consist of furnishing all materials, labor, tools, equipment,
22            services and incidentals necessary to construct the shafts in accordance with the
23            Plans, the Standard Specifications, and the Special Provisions.
24
25   Materials
26   2.01 Casing
27
28       A.   All permanent casing shall be of steel base metal conforming to ASTM A 36. All
29            permanent casing shall be of ample strength to resist damage and deformation
30            from transportation and handling, installation stresses, and all pressures and forces
31            acting on the casing.
32
33            All temporary casing shall be a smooth wall structure of steel base metal, except
34            where corrugated metal pipe is shown in the Plans as an acceptable alternative
35            material. All temporary casing shall be of ample strength to resist damage and
36            deformation from transportation and handling, installation and extraction stresses,
37            and all pressures and forces acting on the casing. The casing shall be capable of
38            being removed without deforming and causing damage to the completed shaft, and
39            without disturbing the surrounding soil.
40
41       B.   Permanent casing is defined as casing designed as part of the shaft structure and
42            installed to remain in place after construction is complete. Temporary casing is
43            defined as casing installed to facilitate shaft construction only, which is not
44            designed as part of the shaft structure, and which shall be completely removed
45            after shaft construction is complete, unless otherwise shown in the Plans.
46
47       C.   The casing shall be watertight and clean prior to placement in the excavation.
48

     SHAFT.BS1                                     1                           JULY 15, 2010
 1       D.   The outside diameter of the casing shall not be less than the specified diameter of
 2            the shaft. The inside diameter of the casing shall not be greater than the specified
 3            diameter of the shaft plus six inches, except as otherwise noted for shafts 5’-0” or
 4            less in diameter, and as otherwise noted in subsection 3.03.C of this Special
 5            Provision for temporary telescoping casing. The inside diameter of casings for
 6            shafts 5’-0” or less in diameter shall not be greater than the specified diameter of
 7            the shaft plus 1’-0”.
 8
 9       E.   Where the minimum thickness of the casing is specified in the Plans, it is specified
10            to satisfy structural design requirements only. The Contractor shall increase the
11            casing thickness as necessary to satisfy the requirements of item A of this section.
12
13   2.02 Reinforcing Steel
14
15       A.   Reinforcing steel used in the construction of shafts shall conform to Section 9-07.
16
17       B.   Steel reinforcing bar centralizers shall be steel, conforming to the details shown in
18            the Plans. The Contractor may propose the use of alternative steel reinforcing bar
19            devices as part of item 7 of the shaft installation plan submittal, as specified in
20            subsection 3.02.B of this Special Provision, subject to the Engineer’s review and
21            approval of such devices.
22
23   2.03 Concrete
24
25       A.   Concrete used in the construction of shafts shall be Class 4000P conforming to
26            Section 6-02.
27
28       B.   When shafts are constructed in water, the concrete used for the casing shoring
29            seal shall be Class 4000W conforming to Section 6-02.
30
31   2.04 Slurry
32
33   Slurry shall conform to one of the following:
34
35       A.   Mineral Slurry
36
37            1.   Mineral slurry shall conform to the following requirements:




     SHAFT.BS1                                       2                           JULY 15, 2010
1
                              Property                    Test               Requirement
                       Density (pcf)              Mud Weight (Density)         64.3 to 75
                                                  API 13B-1, Section 1
                       Viscosity                  Marsh Funnel and              26 to 50
                       (seconds/quart)            Cup API 13b-1,
                                                  Section 2.2
                       PH                         Glass Electrode, pH            8 to 11
                                                  Meter, or pH Paper

                       Sand Content               Sand API 13B-1,
                       (percent)                  Section 5


                       -prior to final cleaning                                 4.0 max.

                       -immediately prior to
                       placing concrete
                                                                                4.0 max.

 2
 3                    Use of mineral slurry in salt water installations will not be allowed.
 4
 5                    Slurry temperature shall be at least 40F when tested.
 6
 7      B.   Synthetic Slurries
 8
 9           1.   Synthetic slurries shall be used in conformance with the manufacturer's
10                recommendations, the quality control plan specified in subsection 3.02.B.4 of
11                this Special Provision, and these Special Provisions. The following synthetic
12                slurries are approved as slurry systems, with additives that have been load
13                tested for the California Department of Transportation:
14
                           Product                         Manufacturer
                        Novagel               Geo-Tech Services, LLC
                                              220 North Zapata Highway, Suite 11A
                                              Laredo, TX 78043-4464
                        ShorePac GCV          CETCO
                                              1500 West Shure Drive
                                              Arlington Heights IL, 60004
                        SlurryPro CDP         KB International, LLC
                                              Suite 216, 735 Broad Street
                                              Chattanooga, TN 37402-1855
                        Super Mud*            PDS Company
                                              8140 East Rosecrans Ave.
                                              Paramount, CA 90723-2754
15
16                *Approval as a product applies to the liquid product only.
17


     SHAFT.BS1                                      3                            JULY 15, 2010
 1                 Other synthetic slurry products may be approved for use provided the product
 2                 meets the acceptance criteria established by WSDOT, including status as an
 3                 approved synthetic slurry (with load tested additives) with the California
 4                 Department of Transportation (Caltrans).
 5
 6            2.   The sand content of synthetic slurry prior to final cleaning and immediately
 7                 prior to placing concrete shall be less than 2.0 percent, in accordance with API
 8                 13B-1, Section 5.
 9
10            For projects with shafts constructed in salt water when the geotechnical report
11            specifies that the use of fresh water for synthetic slurry is feasible and when the
12            Contracting Agency wishes to restrict the water for synthetic slurry to fresh water
13            only, item 3 shall be added at the end of subsection B as follows:
14
15            3. Salt water shall not be used with synthetic slurry for shafts. Fresh water only
16               shall be used.
17
18       C.   Water Slurry (with or without site soils)
19
20            1.   Water with or without site soils may be used as slurry when casing is used for
21                 the entire length of the drilled hole. Use of water slurry without full length
22                 casing may only be used with the approval of the Engineer.
23
24            2.   Water slurry shall conform to the following requirements:
25
                              Property                     Test               Requirement
                         Density (pcf)           Mud Weight                       65 max.
                                                 (Density) API 13B-1,
                                                 Section 1
                         Sand Content            Sand API 13B-1,                 1.0 max.
                         (percent)               Section 5

26
27                     Use of water slurry in salt water installations will not be allowed.
28
29                     Slurry temperature shall be at least 40F when tested.
30
31   2.05 Access Tubes for Crosshole Sonic Log Testing
32
33       A.   Access tubes for crosshole sonic log testing shall be steel pipe of 0.145 inches
34            minimum wall thickness and at least 1-1/2 inch inside diameter.
35
36       B.   The access tubes shall have a round, regular inside diameter free of defects and
37            obstructions, including all pipe joints, in order to permit the free, unobstructed
38            passage of 1.3 inch maximum diameter source and receiver probes used for the
39            crosshole sonic log tests. The access tubes shall be watertight, free from
40            corrosion with clean internal and external faces to ensure good bond between the
41            concrete and the access tubes. The access tubes shall be fitted with watertight
42            threaded PVC caps on the bottom, and shall be fitted with watertight PVC caps,
43            secured in position by means as approved by the Engineer, on the top.

     SHAFT.BS1                                      4                             JULY 15, 2010
 1
 2   2.06 Grout
 3
 4       A.   Grout for filling the access tubes at the completion of the crosshole sonic log tests
 5            shall be a neat cement grout conforming to Section 9-20.3 with a maximum
 6            water/cement ratio of 0.45.
 7
 8   Construction Requirements
 9   3.01 Quality Assurance
10
11       A.   Shaft Construction Tolerances
12
13            1.   Shafts shall be constructed so that the center at the top of the shaft is within
14                 the following horizontal tolerances:
15
16                          Shaft Diameter                 Tolerance
17
18                     Less than or equal to 2'-0"              3"
19                     Greater than 2’-0” and less than 5'-0"   4"
20                         5'-0" or larger                      6"
21
22            2.   Shafts shall be within 1.5 percent of plumb. For rock excavation, allowable
23                 tolerance can be increased to 2 percent max.
24
25            3.   During drilling or excavation of the shaft, the Contractor shall make frequent
26                 checks on the plumbness, alignment, and dimensions of the shaft. Any
27                 deviation exceeding the allowable tolerances shall be corrected with a
28                 procedure approved by the Engineer.
29
30            4.   Shaft steel reinforcing bar placement tolerances shall conform to Section 6-
31                 02.3(24)C.
32
33       B.   Nondestructive Testing of Shafts
34
35            1.   Unless otherwise specified in this Special Provision, the Contracting Agency
36                 will perform crosshole sonic log testing of specific shafts, except for those
37                 constructed completely in the dry, selected in accordance with subsection
38                 3.09.A of this Special Provision. The Contractor shall accommodate the
39                 crosshole sonic log testing by furnishing and installing access tubes in
40                 accordance with subsection 3.06.A of this Special Provision.
41
42       C.   Shaft Preconstruction Conference
43
44            1.   A shaft preconstruction conference shall be held at least five working days
45                 prior to the Contractor beginning any shaft construction work at the site to
46                 discuss construction procedures, personnel, and equipment to be used, and
47                 other elements of the approved shaft installation plan as specified in
48                 subsection 3.02.B of this Special Provision. Those attending shall include:
49
50                     a.   (representing the Contractor)    The superintendent, on site
51                          supervisors, and all foremen in charge of excavating the shaft,
52                          placing the casing and slurry as applicable, placing the steel

     SHAFT.BS1                                     5                           JULY 15, 2010
 1                          reinforcing bars, and placing the concrete. If synthetic slurry is used
 2                          to construct the shafts, the slurry manufacturer's representative or
 3                          approved Contractor employees trained in the use of the synthetic
 4                          slurry shall also attend.
 5
 6                     b.   (representing the Contracting Agency) The Project Engineer, key
 7                          inspection personnel, and representatives from the WSDOT
 8                          Construction Office and Materials Laboratory Geotechnical Branch.
 9
10            2.   If the Contractor proposes a significant revision of the approved shaft
11                 installation plan, as determined by the Engineer, an additional conference
12                 shall be held before any additional shaft construction operations are
13                 performed.
14
15   3.02 Submittals
16
17       A.   Construction Experience
18
19            1.   Prior to the start of shaft construction, the Contractor shall electronically
20                 submit a project reference list to the Engineer for approval verifying the
21                 successful completion by the Contractor of at least three separate foundation
22                 projects with shafts of diameters and depths similar to or larger than those
23                 shown in the Plans, and ground conditions similar to those identified in the
24                 Contract. A brief description of each listed project shall be provided along with
25                 the name and current phone number of the project owner or the owner's
26                 Contractor.
27
28            2.   Prior to the start of shaft construction, the Contractor shall electronically
29                 submit a list identifying the on-site supervisors, and drill rig operators
30                 potentially assigned to the project to the Engineer for approval. The list shall
31                 contain a brief description of each individual's experience in shaft excavation
32                 operations, and placement of assembled steel reinforcing bar cages and
33                 concrete in shafts. The individual experience lists shall be limited to a single
34                 page for each supervisor or operator.
35
36                     a.   On-site supervisors shall have a minimum two years experience in
37                          supervising construction of shaft foundations of similar size (diameter
38                          and depth) and scope to those shown in the Plans, and similar
39                          geotechnical conditions to those described in the boring logs and
40                          summary of geotechnical conditions. The work experience shall be
41                          direct supervisory responsibility for the on-site shaft construction
42                          operations. Project management level positions indirectly supervising
43                          on-site shaft construction operations is not acceptable for this
44                          experience requirement.
45
46                     b.   Drill rig operators shall have a minimum one year experience in
47                          construction of shaft foundations.
48
49            3.   The Engineer will approve or reject the Contractor's qualifications and field
50                 personnel within 10 working days after receipt of the submission. Work shall
51                 not be started on any shaft until the Contractor's qualifications and field
52                 personnel are approved by the Engineer. The Engineer may suspend the

     SHAFT.BS1                                     6                            JULY 15, 2010
 1               shaft construction if the Contractor substitutes unapproved personnel. The
 2               Contractor shall be fully liable for the additional costs resulting from the
 3               suspension of work and no adjustments in contract time resulting from the
 4               suspension of work will be allowed.
 5
 6      B.   Shaft Installation Plan
 7
 8           The Contractor shall electronically submit a shaft installation narrative for approval
 9           by the Engineer. In preparing the narrative, the Contractor shall reference the
10           available subsurface data provided in the contract test hole boring logs, the
11           Summary of Geotechnical Conditions provided in the Appendix to the Special
12           Provisions, and the geotechnical report(s) prepared for this project. This narrative
13           shall provide at least the following information:
14
15               1.   Proposed overall construction operation sequence.
16
17               2.   Description, size and capacities of proposed equipment, including but not
18                    limited to cranes, drills, auger, bailing buckets, final cleaning equipment
19                    and drilling unit. The narrative shall describe why the equipment was
20                    selected, and describe equipment suitability to the anticipated site
21                    conditions and work methods. The narrative shall include a project history
22                    of the drilling equipment demonstrating the successful use of the
23                    equipment on shafts of equal or greater size in similar soil/rock conditions.
24                    The narrative shall also include details of shaft excavation and cleanout
25                    methods.
26
27               3.   Details of the method(s) to be used to ensure shaft stability (i.e.,
28                    prevention of caving, bottom heave, etc. using temporary casing, slurry,
29                    or other means) during excavation (including pauses and stoppages
30                    during excavation) and concrete placement. If permanent casings are
31                    required, casing dimensions and detailed procedures for installation shall
32                    be provided.
33
34               4.   Detailed procedures for mixing, using and maintaining the slurry shall be
35                    provided. A detailed mix design (including all additives and their specific
36                    purpose in the slurry mix), and a discussion of its suitability to the
37                    anticipated subsurface conditions, shall also be provided for the proposed
38                    slurry.
39
40                    The submittal shall include a detailed plan for quality control of the
41                    selected slurry, including tests to be performed, test methods to be used,
42                    and minimum and/or maximum property requirements which must be met
43                    to ensure that the slurry functions as intended, considering the anticipated
44                    subsurface conditions and shaft construction methods, in accordance with
45                    the slurry manufacturer's recommendations and these Special Provisions.
46                    As a minimum, the slurry quality control plan shall include the following
47                    tests:
48




     SHAFT.BS1                                    7                            JULY 15, 2010
                            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          Sand, API 13B-1, Section 5
                            Content

 1
 2               5.   Description of the method used to fill or eliminate all voids below the top
 3                    of shaft between the plan shaft diameter and excavated shaft diameter,
 4                    when permanent casing is specified.
 5
 6               6.   Details of concrete placement, including proposed operational procedures
 7                    for pumping methods, and a sample uniform yield form to be used by the
 8                    Contractor for plotting the approximate volume of concrete placed versus
 9                    the depth of shaft for all shaft concrete placement (except concrete
10                    placement in the dry).
11
12               7.   When shafts are constructed in water, the submittal shall include seal
13                    thickness calculations, seal placement procedure, and descriptions of
14                    provisions for casing shoring dewatering and flooding.
15
16               8.   Description and details of the storage and disposal plan for excavated
17                    material, and drilling slurry (if applicable).
18
19               9.   Reinforcing steel shop drawings, details of reinforcement placement,
20                    including bracing, centering, and lifting methods, and the method to
21                    assure the reinforcing cage position is maintained during construction,
22                    including use of bar boots and/or rebar cage base plates, and including
23                    placement of rock backfill below the bottom of shaft elevation provided the
24                    conditions of subsection 3.05.D of this Special Provision are satisfied.
25
26                    The reinforcing steel assembly and installation plan shall include:
27
28                        a.     Procedure and sequence of steel reinforcing bar cage assembly.
29
30                        b.     The tie pattern, tie types and tie wire gages for all ties on
31                               permanent reinforcing and temporary bracing.
32
33                        c.     Number and location of primary handling steel reinforcing bars
34                               used during lifting operations.
35
36                        d.     Type and location of all steel reinforcing bar splices.
37
38                        e.     Details and orientation of all internal cross-bracing, including a
39                               description of connections to the steel reinforcing bar cage.


     SHAFT.BS1                                      8                            JULY 15, 2010
 1
 2                         f.   Description of how temporary bracing is to be removed.
 3
 4                         g.   Location of support points during transportation.
 5
 6                         h.   Cage weight and location of the center of gravity.
 7
 8                         i.   Number and location of pick points used for lifting for installation,
 9                              and for transport (if assembled off-site).
10
11                         j.   Crane charts and a description and/or catalog cuts for all
12                              spreaders, blocks, sheaves and chockers used to equalize or
13                              control lifting loads.
14
15                         k.   The sequence and minimum inclination angle at which
16                              intermediate belly rigging lines (if used) are released.
17
18                         l.   Pick point loads at 0, 45, 60 and 90 degrees and at all
19                              intermediate stages of inclination where rigging lines are
20                              engaged or slackened.
21
22                         m. Methods and temporary supports required for cage splicing.
23
24                         n.   For picks involving multiple cranes, the relative locations of the
25                              boom tips at various stages of lifting, along with corresponding
26                              net horizontal forces imposed on each crane.
27
28                         For shafts with a 6’-0” minimum nominal diameter and/or shafts with
29                         60’-0” minimum length, the reinforcing steel assembly and installation
30                         plan shall be prepared and submitted in accordance with Section 6-
31                         01.9.
32
33           The Engineer will evaluate the shaft installation plan for conformance with the
34           Plans, Specifications and Special Provisions, within the review time specified in
35           Section 6-01.9. A Shaft Installation Plan Submittal Teleconference Meeting will be
36           scheduled by the Contracting Agency following review of the Contractor’s initial
37           submittal of the plan and prior to Contracting Agency formal response to the initial
38           submittal. Teleconference participants shall include the following:
39
40                a.   (representing the Contractor) The superintendent, on-site supervisors,
41                     and other Contractor personnel involved in the preparation of the shaft
42                     installation plan.
43
44                b.   (representing the Contracting Agency)       The Project Engineer, key
45                     inspection personnel, and representatives from the Materials Laboratory
46                     Geotechnical Branch, and the WSDOT Construction Office.
47
48      C.   Slurry Technical Assistance
49
50           1.   If slurry other than water slurry is used to construct the shafts, the Contractor
51                shall provide or arrange for technical assistance in the use of the slurry as


     SHAFT.BS1                                     9                            JULY 15, 2010
 1                 specified in subsection 3.04.A.1 of this Special Provision. The Contractor shall
 2                 electronically submit the following to the Engineer:
 3
 4                     a.    The name and current phone number of the slurry manufacturer's
 5                           technical representative assigned to the project, and the frequency of
 6                           scheduled visits to the project site by the synthetic slurry
 7                           manufacturer’s representative.
 8
 9                     b.    The name(s) of the Contractor’s personnel assigned to the project
10                           and trained by the slurry manufacturer in the proper use of the slurry.
11                           The submittal shall include a signed training certification letter from
12                           the slurry manufacturer for each trained Contractor’s employee listed,
13                           including the date of the training.
14
15       D.   All submittals shall be in electronic pdf format, and all documents in each pdf shall
16            be legible. All submittals shall be prepared jointly by the Contractor and any
17            subcontractors that will be performing the work.
18
19       E.   Work shall not begin until all the required submittals have been approved in writing
20            by the Engineer. All procedural approvals given by the Engineer will be subject to
21            trial in the field and shall not relieve the Contractor of the responsibility to
22            satisfactorily complete the work.
23
24       If crosshole sonic log testing is to be provided by the Contractor, add subsection 3.02.D
25       as follows, and renumber existing subsections 3.02.D and 3.02.E to 3.02.E and 3.02.F:
26
27       D.   Crosshole Sonic Log Testing Organization and Personnel
28
29            1.   At least seven calendar days prior to beginning shaft construction, the
30                 Contractor shall submit the name of the independent testing organization, and
31                 the names of the personnel, conducting the crosshole sonic log tests to the
32                 Engineer for approval. The submittal shall include documentation that the
33                 qualifications specified below are satisfied.    The independent testing
34                 organization and the testing personnel shall meet the following minimum
35                 qualifications:
36
37                     a.    The testing organization shall have performed crosshole sonic log
38                           tests on a minimum of three deep foundation projects in the last two
39                           years.
40
41                     b.    Personnel conducting the tests for the testing organization shall have
42                           a minimum of one year experience in crosshole sonic log testing and
43                           interpretation.
44
45   3.03 Shaft Excavation
46
47       A.   Shafts shall be excavated to the required depth as shown in the Plans. Shaft
48            excavation operations shall conform to this Special Provision and the shaft
49            installation plan as approved by the Engineer, except as otherwise specified by the
50            Engineer. Once the excavation operation has been started, the excavation shall be
51            conducted in a continuous operation until the excavation of the shaft is completed,

     SHAFT.BS1                                     10                           JULY 15, 2010
 1          except for pauses and stops as noted, using approved equipment capable of
 2          excavating through the type of material expected. Pauses during this excavation
 3          operation, except for casing splicing, tooling changes, slurry maintenance, and
 4          removal of obstructions, are not allowed.
 5
 6          Pauses, defined as momentary interruptions of the excavation operation, will be
 7          allowed only for casing splicing, tooling changes, slurry maintenance, and removal
 8          of obstructions. Shaft excavation operation interruptions not conforming to this
 9          definition shall be considered stops. Stops for uncased excavations (including
10          partially cased excavations) shall not exceed 16 hours duration. Stops for fully
11          cased excavations, excavations in rock, and excavations with casing seated into
12          rock, shall not exceed 65 hours duration.
13
14          For stops exceeding the time durations specified above, the Contractor shall
15          stabilize the excavation using one or both of the following methods:
16
17               1.   For an uncased excavation, before the end of the work day, install casing
18                    in the hole to the depth of the excavation. The outside diameter of the
19                    casing shall not be smaller than six inches less than either the Plan
20                    diameter of the shaft or the actual excavated diameter of the hole,
21                    whichever is greater. Prior to removing the casing and resumption of
22                    shaft excavation, the annular space between the casing and the
23                    excavation shall be sounded. If the sounding operation indicates that
24                    caving has occurred, the casing shall not be removed and shaft
25                    excavation shall not resume until the Contractor has stabilized the
26                    excavation in accordance with the shaft installation plan conforming to
27                    subsection 3.02.B.3 of this Special Provision.
28
29               2.   For both a cased and uncased excavation, backfill the hole with either
30                    CDF or granular material. The Contractor shall backfill the hole to the
31                    ground surface, if the excavation is not cased, or to a minimum of five feet
32                    above the bottom of casing (temporary or permanent), if the excavation is
33                    cased. Backfilling of shafts with casing fully seated into rock, as
34                    determined by the Engineer, will not be required.
35
36          During stops, the Contractor shall stabilize the shaft excavation to prevent bottom
37          heave, caving, head loss, and loss of ground. The Contractor bears full
38          responsibility for selection and execution of the method(s) of stabilizing and
39          maintaining the shaft excavation, in accordance with Section 1-07.13. Shaft
40          stabilization shall conform to the shaft installation plan in accordance with
41          subsection 3.02.B.3 of this Special Provision.
42
43          If slurry is present in the shaft excavation, the Contractor shall conform to the
44          requirements of subsection 3.04.B of this Special Provision regarding the
45          maintenance of the slurry and the minimum level of drilling slurry throughout the
46          stoppage of the shaft excavation operation, and shall recondition the slurry to the
47          required slurry properties in accordance with subsection 3.04 of this Special
48          Provision prior to recommencing shaft excavation operations.
49
50      It is difficult to properly administer the construction of shafts with a required minimum
51      penetration into rock, glacial till, or glacial deposit with the elevation of the top of hard
52      material not known for each shaft. The problem, simply stated, is because the

     SHAFT.BS1                                    11                             JULY 15, 2010
 1      Contracting Agency requires that the concrete be placed immediately after the
 2      excavation is complete; the depth of excavation cannot be determined until the
 3      elevation of the top of hard material is located; and the steel reinforcing bar cages must
 4      be tied up prior to completion of the excavation.
 5
 6      If this situation occurs on a project, the preferred solution is to have an exploratory hole
 7      located at each shaft so the exact shaft depth is known. If this cannot be
 8      accomplished, the Contracting Agency will pay for 20% more reinforcing steel with the
 9      understanding that some or all of this extra reinforcing steel may be not used in the
10      shafts depending on the exact depth of the excavation. Since the steel reinforcing bar
11      cage must be tied up prior to the completion of the excavation, it is economical for the
12      Contracting Agency to purchase 20% more steel.
13
14      When the Contract requires a minimum penetration into a bearing layer, as opposed to
15      a specified shaft tip elevation, and the bearing layer elevation at each shaft cannot be
16      accurately determined, insert the following at the end of subsection 3.03.A:
17
18           Variations in the bearing layer elevation from that shown in the Plans are
19           anticipated. The Contractor shall have equipment on-site capable of excavating an
20           additional 20 percent of depth below that shown in the Plans.
21
22      Soils consisting of gravel and cobble mixtures, or matrix supported boulders where the
23      matrix is granular, tend to be susceptible to caving and sloughing, and usually require
24      casing to stabilize the shaft side walls. These materials also make vibratory casing
25      installation very difficult and risky for both the Contracting Agency and the Contractor.
26      In such cases, the installation of temporary and/or permanent casing by either a
27      rotating or an oscillating method may be required. When the ADSC/WSDOT Shaft
28      Task Force concurs that such a specific casing installation process is necessary, the
29      following paragraph should be inserted at the end of subsection 3.03.A:
30
31           Shaft casing shall be equipped with cutting teeth or a cutting shoe, and installed by
32           either rotating or oscillating the casing. Installing the casing by vibratory means will
33           not be allowed.
34
35      B.   The Contractor shall furnish and install casings as follows:
36
37                                                                             Upper
38                                                                             And Lower
39               Wall           Wall                           Elev. Of        Elevation Limits
40               Name or        Station or                     Bottom of       for Concurrent
41               Bridge         Bridge      Casing             Required        Casing Placement
42               No.            Pier Number Type               Casing (ft)     with Excavation
43
44               ***$$1$$***    ***$$2$$***     ***$$3$$***    ***$$4$$***     ***$$5$$***
45
46           When installing required temporary or required permanent casings between the
47           upper and lower elevation limits specified above, the casing shall be advanced
48           prior to or concurrently with the excavation. Excavation in advance of the casing
49           tip shall not exceed ***$$6$$*** feet, except that in no case shall shaft excavation
50           and casing placement extend below the bottom of shaft excavation as shown in the
51           Plans.

     SHAFT.BS1                                    12                             JULY 15, 2010
 1
 2           To maintain stable excavations and to facilitate construction, the Contractor may
 3           furnish and install temporary casing in addition to the required casing specified
 4           above. The Contractor shall provide temporary casing at the site in sufficient
 5           quantities to meet the needs of the anticipated construction method.
 6
 7      Prior to establishing values for fill-ins 5 and 6 in subsection 3.03.B above, a meeting
 8      shall be held early in the shaft design process to discuss the casing placement
 9      construction requirements appropriate for the geotechnical and general site conditions.
10      For WSDOT projects, the attendees should include the Bridge and Structures Office,
11      Materials Laboratory Geotechnical Services Branch, Construction Office, and
12      representation from ADSC and other appropriate design and geotechnical consultants
13      assigned to the project. For Local Agency non-WSDOT projects, the attendees should
14      include appropriate design and geotechnical designers and consultants assigned to the
15      project, and representation from ADSC. Arrangements for ADSC representation at
16      such meetings should be made through Alan Macnab at (206) 575-8248. If the
17      geotechnical conditions present at the site do not require advancing casing concurrent
18      with shaft excavation, the appropriate fill-in for fill-ins 5 and 6 is “N/A” or “Not
19      Applicable”.
20
21      C.   Where the acceleration coefficient used for seismic design of the structure, as
22           specified in the General Notes of the structure Plans, is less than or equal to 0.16,
23           the Contractor may use temporary telescoping casing for the shafts at any bridge
24           intermediate or interior pier, subject to the following conditions:
25
26               1.   The Contractor shall submit the request to use temporary telescoping
27                    casing to the Engineer for approval. The request shall specify the
28                    diameters of the temporary telescoping casing, and shall specify the
29                    shafts where use is requested. The Contractor shall not proceed with the
30                    use of temporary telescoping casing until receiving the Engineer’s
31                    approval.
32
33               2.   The minimum diameter of the shaft shall be as shown in the Plans.
34
35               3.   The temporary telescoping casing shall conform to subsections 2.01.A,
36                    2.01.B, 2.01.C, and 2.01.E of this Special Provision.
37
38           The Contractor may use temporary telescoping casing for the shafts of any bridge
39           end pier, regardless of the acceleration coefficient used for the seismic design of
40           the structure, subject to conditions 2 and 3 specified above, and the following two
41           additional conditions:
42
43               4.   A maximum of two telescoping casing diameter changes will be allowed.
44
45               5.   The maximum diameter change at each casing diameter transition shall
46                    be twelve inches.
47
48      For bridges designed under certain design conditions where the option of temporary
49      telescoping casing for the shafts at a bridge end pier is not appropriate for the overall
50      design behavior of the structure, the last paragraph of subsection 3.03.C, including
51      conditions 4 and 5, should be deleted.


     SHAFT.BS1                                   13                           JULY 15, 2010
 1
 2      D.   The Contractor shall conduct casing installation and removal operations and shaft
 3           excavation operations such that the adjacent soil outside the casing and shaft
 4           excavation for the full height of the shaft is not disturbed. Disturbed soil is defined
 5           as soil whose geotechnical properties have been changed from those of the
 6           original in-situ soil, and whose altered condition adversely affects the structural
 7           integrity of the shaft foundation.
 8
 9      E.   The Contractor shall use appropriate means such as a cleanout bucket or air lift to
10           clean the bottom of the excavation of all shafts. No more than 2 inches of loose or
11           disturbed material shall be present at the bottom of the shaft just prior to placing
12           concrete.
13
14      F.   The excavated shaft shall be inspected and approved by the Engineer prior to
15           proceeding with construction. The bottom of the excavated shaft shall be sounded
16           with an airlift pipe, a tape with a heavy weight attached to the end of the tape, or
17           other means acceptable to the Engineer to determine that the shaft bottom meets
18           the requirements in the Contract.
19
20      G. When obstructions are encountered, the Contractor shall notify the Engineer
21         promptly. An obstruction is defined as a specific object (including, but not limited
22         to, boulders, logs, and man made objects) encountered during the shaft excavation
23         operation which prevents or hinders the advance of the shaft excavation. When
24         efforts to advance past the obstruction to the design shaft tip elevation result in the
25         rate of advance of the shaft drilling equipment being significantly reduced relative
26         to the rate of advance for the portion of the shaft excavation in the geological unit
27         that contains the obstruction, then the Contractor shall remove, break-up, or push
28         aside, the obstruction under the provisions of subsection 5.01.B of this Special
29         Provision. The method of dealing with such obstructions, and the continuation of
30         excavation shall be as proposed by the Contractor and approved by the Engineer.
31
32      H.   When permanent casing is specified, excavation shall conform to the specified
33           outside diameter of the shaft. After the casing has been filled with concrete, all
34           void space occurring between the casing and shaft excavation shall be filled with a
35           material which approximates the geotechnical properties of the in-situ soils, in
36           accordance with the shaft installation plan specified in subsection 3.02.B.5 of this
37           Special Provision and as approved by the Engineer.
38
39      I.   Drilling equipment shall not be operated from an existing bridge, except as
40           otherwise noted. If necessary and safe to do so, and if the Contractor submits a
41           written request to the Engineer in accordance with Section 6-01.6, the Engineer
42           may approve the operation of drilling equipment on a bridge.
43
44      J.   When shafts are constructed in water, the Contractor shall construct a seal
45           between the casing shoring and the upper portion of the permanent casing for the
46           shaft as shown in the Plans, in accordance with the shaft installation plan specified
47           in subsection 3.02.B.7 of this Special Provision, and as approved by the Engineer.
48
49           The seal thickness shown in the Plans is designed to resist the hydrostatic uplift
50           force with the corresponding seal weight and adhesion of the seal to the
51           permanent casing and the casing shoring of 20 psi, based on the casing shoring
52           dimension and the seal vent water surface elevation specified in the Plans. If the

     SHAFT.BS1                                    14                            JULY 15, 2010
 1            Contractor uses a casing shoring diameter other than that specified in the Plans,
 2            the Contractor shall submit a revised seal design to the Engineer for approval in
 3            accordance with subsection 3.02.B.7 of this Special Provision.
 4
 5            If, in the opinion of the Engineer, water conditions at the time of construction allow
 6            the seal vent water surface elevation to be lowered, the Contractor may revise the
 7            casing shoring seal by submitting a revised seal design to the Engineer for
 8            approval in accordance with subsection 3.02.B.7 of this Special Provision.
 9
10       K.   The Contractor shall use slurry, in accordance with subsection 3.04 of this Special
11            Provision, to maintain a stable excavation during excavation and concrete
12            placement operations once water begins to enter the shaft excavation at an
13            infiltration rate of 12 inches of depth or more in one hour and remain present at a
14            three inch depth or greater.
15
16       For certain projects where the geotechnical conditions allow the possibility of
17           performing shaft excavation in a cased hole beneath the water table level without
18           the need for slurry to ensure the stability of the bottom of the excavation,
19           subsection 3.03.K may be replaced with the following text, provided that
20           documented approval of the use of this provision is presented in the project’s
21           geotechnical report.
22
23       K.   The Contractor shall use slurry, in accordance with subsection 3.04 of this Special
24            Provision, to maintain a stable excavation during excavation and concrete
25            placement operations once water begins to enter the shaft excavation at an
26            infiltration rate of 12 inches of depth or more in one hour and remain present at a
27            three inch depth or greater, except as otherwise noted. If the Contractor is utilizing
28            casing that is adequately sealed into competent soils such that the water cannot
29            enter the excavation, the Contractor may, with the Engineer’s approval, continue
30            excavation in wet soils provided the water level within the casing does not rise or
31            exhibit flow.
32
33   3.04 Slurry Installation Requirements
34
35       A.   Slurry Technical Assistance
36
37            1.   If slurry other than water slurry is used, the manufacturer's representative, as
38                 identified to the Engineer in accordance with subsection 3.02.C of this Special
39                 Provision, shall:
40
41                     a.   provide technical assistance for the use of the slurry,
42
43                     b.   shall be at the site prior to introduction of the slurry into a drilled hole,
44                          and
45
46                     c.   shall remain at the site during the construction and completion of a
47                          minimum of one shaft to adjust the slurry mix to the specific site
48                          conditions.
49




     SHAFT.BS1                                      15                              JULY 15, 2010
 1      For certain projects where the geotechnical conditions vary enough from one shaft site
 2      to another to affect how slurry is used at each shaft site, add subsection 3.04.A.1.d as
 3      follows:
 4
 5      d. shall be present during construction and completion of at least one shaft at the
 6         following specific shaft sites:
 7               *** $$7$$ ***
 8
 9           2.   After the manufacturer’s representative is no longer present at the site, the
10                Contractor’s employee trained in the use of the slurry, as identified to the
11                Engineer in accordance with subsection 3.02.C of this Special Provision, shall
12                be present at the site throughout the remainder of shaft slurry operations for
13                this project to perform the duties specified in items 1a through 1c above.
14
15      B.   Minimum Level of Slurry in the Excavation
16
17           1.   When slurry is used to maintain a stable excavation, the slurry level in the
18                excavation shall be maintained above the groundwater level the greater of the
19                following dimensions, except as otherwise noted in subsection 3.04.B.3 of this
20                Special Provision:
21
22                    a.   not less than five feet for mineral slurries,
23
24                    b.   not less than ten feet for water slurries,
25
26                    c.   not less than ten feet for synthetic slurries,
27
28                    d.   one shaft diameter,
29
30                    e.   dimension as required to provide and maintain a stable hole.
31
32                The Contractor shall provide casing, or other means, as necessary to meet
33                these requirements.
34
35           2.   The slurry level shall be maintained above all unstable zones a sufficient
36                distance to prevent bottom heave, caving or sloughing of those zones.
37
38           3.   Throughout all stops in shaft excavation operations, as specified in subsection
39                3.03.A of this Special Provision, the Contractor shall monitor and maintain the
40                slurry level in the excavation the greater of the following elevations:
41
42                    a.   no lower than the water level elevation outside the shaft,
43
44                    b.   elevation as required to provide and maintain a stable hole.
45
46      C.   Slurry Sampling and Testing
47
48           1.   Mineral slurry and synthetic slurry shall be mixed and thoroughly hydrated in
49                slurry tanks, ponds, or storage areas. The Contractor shall draw sample sets
50                from the slurry storage facility and test the samples for conformance with the
51                appropriate specified material properties before beginning slurry placement in


     SHAFT.BS1                                     16                          JULY 15, 2010
 1                the drilled hole. Mineral slurry shall conform to the material specifications in
 2                subsection 2.04.A of this Special Provision. Synthetic slurry shall conform to
 3                the quality control plan included in the shaft installation plan in accordance
 4                with subsection 3.02.B.4 of this Special Provision and as approved by the
 5                Engineer. A sample set shall be composed of samples taken at mid-height
 6                and within two feet of the bottom of the storage area.
 7
 8           2.   The Contractor shall sample and test all slurry in the presence of the Engineer,
 9                unless otherwise directed. The date, time, names of the persons sampling
10                and testing the slurry, and the results of the tests shall be recorded. A copy of
11                the recorded slurry test results shall be submitted to the Engineer at the
12                completion of each shaft, and during construction of each shaft when
13                requested by the Engineer.
14
15           3.   Sample sets of all slurry, composed of samples taken at mid-height and within
16                two feet of the bottom of the shaft, shall be taken and tested during drilling as
17                necessary to verify the control of the properties of the slurry. As a minimum,
18                sample sets of synthetic slurry shall be taken and tested at least once every
19                four hours after beginning its use during each shift. Sample sets of all slurry
20                shall be taken and tested at least once every two hours if the slurry is not
21                recirculated in the drilled hole or if the previous sample set did not have
22                consistent specified properties. All slurry shall be recirculated, or agitated with
23                the drilling equipment, when tests show that the sample sets do not have
24                consistent specified properties.
25
26           4.   Sample sets of all slurry, as specified, shall be taken and tested prior to final
27                cleaning of the bottom of the hole and again just prior to placing concrete.
28                Cleaning of the bottom of the hole and placement of the concrete shall not
29                start until tests show that the samples taken at mid-height and within two feet
30                of the bottom of the hole have consistent specified properties.
31
32      D.   The Contractor shall clean, recirculate, de-sand, or replace the slurry to maintain
33           the required slurry properties.
34
35      E.   The Contractor shall demonstrate to the satisfaction of the Engineer that stable
36           conditions are being maintained. If the Engineer determines that stable conditions
37           are not being maintained, the Contractor shall immediately take action to stabilize
38           the shaft. The Contractor shall submit a revised shaft installation plan which
39           addresses the problem and prevents future instability. The Contractor shall not
40           continue with shaft construction until the damage which has already occurred is
41           repaired in accordance with the specifications, and until receiving the Engineer's
42           approval of the revised shaft installation plan.
43
44      F.   When mineral slurry, conforming to subsection 2.04.A of this Special Provision, is
45           used to stabilize the unfilled portion of the shaft, the Contractor shall remove the
46           excess slurry buildup inside of the shaft diameter prior to continuing with concrete
47           placement. The Contractor shall use the same methods of shaft excavation and
48           the same diameter of drill tolls to remove the excess slurry buildup as was used to
49           excavate the shaft to its current depth.
50
51      G. The Contractor shall dispose of the slurry as specified in the shaft installation plan
52         as approved by the Engineer, and in accordance with the following requirements:

     SHAFT.BS1                                     17                            JULY 15, 2010
 1
 2                1.   Water slurry may be infiltrated to uplands within the confines of the
 3                     Contracting Agency Right Of Way for the project, provided that the
 4                     groundline at the disposal site is at least five feet above the current water
 5                     table, and that disposal operations conform to the temporary erosion and
 6                     sedimentation control (TESC) requirements established for this project.
 7                     For the purposes of water slurry disposal, upland is defined as an area
 8                     that has no chance of discharging directly to waters of the State, including
 9                     wetlands or conveyances that indirectly lead to wetlands or waters of the
10                     State.
11
12                2.   Synthetic and mineral slurries shall be contained and disposed of at a
13                     waste water treatment facility or into a sanitary sewer in accordance with
14                     the Contractor's permit requirements.
15
16   3.05 Assembly And Placement Of Reinforcing Steel
17
18       A.   The reinforcing cage shall be rigidly braced to retain its configuration during
19            handling and construction. Individual or loose bars will not be permitted. The
20            Contractor shall show bracing and any extra reinforcing steel required for
21            fabrication of the cage on the shop drawings. Shaft reinforcing bar cages shall be
22            supported on a continuous surface to the extent possible. All rigging connections
23            shall be located at primary handling bars, as identified in the reinforcing steel
24            assembly and installation plan as approved by the Engineer. Internal bracing is
25            required at each support and lift point.
26
27       B.   The reinforcement shall be carefully positioned and securely fastened to provide
28            the minimum clearances listed below, and to ensure that no displacement of the
29            reinforcing steel bars occurs during placement of the concrete. The steel
30            reinforcing bars shall be securely held in position throughout the concrete
31            placement operation. The Contractor shall submit details of the proposed
32            reinforcing cage centralizers along with the shop drawings. The reinforcing steel
33            centralizers at each longitudinal space plane shall be placed at least at the quarter
34            points around the circumference of the steel reinforcing bar cage, and at a
35            maximum longitudinal spacing of either 2.5 times the shaft diameter or 20’-0”,
36            whichever is less.
37
38       C.   Place bars as shown in the contract plans with minimum concrete cover as shown
39            in the table below.
40
41                Shaft Diameter                    Minimum Concrete Cover
42
43
44                Less than or equal to 3'-0"                   3"
45                Greater than 3’-0”
46                and less than 5'-0"                           4"
47                5'-0" or larger                               6"
48
49       D.   For shafts with temporary casing within 15 feet of the bottom of shaft elevation as
50            specified in the Plans, the Contractor may place quarry spalls or other rock backfill
51            approved by the Engineer into the shaft below the specified bottom of shaft
52            elevation as a means to support the steel reinforcing bar cage, provided that the

     SHAFT.BS1                                    18                            JULY 15, 2010
 1            materials and means to accomplish this have been addressed by the shaft
 2            installation plan as approved by the Engineer, as specified in subsection 3.02.B.9
 3            of this Special Provision. The use of bar boots and/or rebar cage base plates is
 4            required when quarry spalls or other rock backfill is placed at the base of the shaft
 5            excavation.
 6
 7       E.   Shaft excavation shall not be started until the Contractor has received approval
 8            from the Engineer for the reinforcing steel centralizers required when the casing is
 9            to be pulled during concrete placement.
10
11       When the Contract requires a minimum penetration into a bearing layer, as opposed to
12       a specified shaft tip elevation, and the bearing layer elevation at each shaft cannot be
13       accurately determined, add subsection 3.05.F as follows:
14
15       F.   For those shafts with a specified minimum penetration into the bearing layer and
16            no specified tip elevation, the Contractor shall furnish each shaft steel reinforcing
17            bar cage, including access tubes for crosshole sonic log testing in accordance with
18            subsection 3.06 of this Special Provision, 20 percent longer than specified in the
19            Plans. The Contractor shall add the increased length to the bottom of the cage.
20            The Contractor shall trim the shaft steel reinforcing bar cage to the proper length
21            prior to placing it into the excavation. If trimming the cage is required and access
22            tubes for crosshole sonic log testing are attached to the cage, the Contractor shall
23            either shift the access tubes up the cage, or cut the access tubes provided that the
24            cut tube ends are adapted to receive the watertight cap as specified.
25
26   3.06 Access Tubes for Crosshole Sonic Log Testing
27
28       A.   The Contractor shall install access tubes for crosshole sonic log testing in all
29            shafts, except as otherwise noted, to permit access for the crosshole sonic log test
30            probes. If, in the opinion of the Engineer, the condition of the shaft excavations
31            permit shaft construction in the dry, the Engineer may specify that the access
32            tubes be omitted.
33
34       B.   The Contractor shall securely attach the access tubes to the interior of the
35            reinforcement cage of the shaft. One access tube shall be furnished and installed
36            for each foot of shaft diameter, rounded to the nearest whole number, as shown in
37            the Plans. The number of access tubes for shaft diameters specified as “X feet 6
38            inches” shall be rounded up to the next higher whole number. The access tubes
39            shall be placed around the shaft, inside the spiral or hoop reinforcement and
40            bundled with the vertical reinforcement. Where circumferential components of the
41            rebar cage bracing system prevent bundling the access tubes directly to the
42            vertical reinforcement, the access tubes shall be placed inside the circumferential
43            components of the rebar cage bracing system as close as possible to the nearest
44            vertical steel reinforcement bar.
45
46       C.   The access tubes shall be installed in straight alignment and as near to parallel to
47            the vertical axis of the reinforcement cage as possible. The access tubes shall
48            extend from the bottom of the reinforcement cage to at least two feet above the top
49            of the shaft. Splice joints in the access tubes, if required to achieve full length
50            access tubes, shall be watertight. The Contractor shall clear the access tubes of
51            all debris and extraneous materials before installing the access tubes. The tops of


     SHAFT.BS1                                    19                           JULY 15, 2010
 1            access tubes shall be de-burred. Care shall be taken to prevent damaging the
 2            access tubes during reinforcement cage installation and concrete placement
 3            operations in the shaft excavation.
 4
 5       D.   The access tubes shall be filled with potable water before concrete placement, and
 6            the top watertight PVC caps shall be reinstalled and secured in accordance with
 7            subsection 2.05.B of this Special Provision. The Contractor shall keep all of a
 8            shaft’s access tubes full of water through the completion of CSL testing of that
 9            shaft. When temperatures below freezing are possible, the Contractor shall protect
10            the access tubes against freezing by wrapping the exposed tubes with insulating
11            material, adding anti-freeze to the water in the tubes, or other methods as
12            approved by the Engineer.
13
14   3.07 Placing Concrete
15
16       A.   Concrete placement shall commence immediately after completion of excavation
17            by the Contractor and inspection by the Engineer.               Immediately prior to
18            commencing concrete placement, the shaft excavation and the properties of the
19            slurry (if used) shall conform to subsections 3.03.E and 3.04, respectively, of this
20            Special Provision. Concrete placement shall continue in one operation to the top of
21            the shaft, or as shown in the Plans. The Contractor shall place concrete between
22            the upper construction joint of the shaft and the top of the shaft in the dry.
23
24            During concrete placement, the Contractor shall monitor, and minimize, the
25            difference in the level of concrete inside and outside of the steel reinforcing bar
26            cage. The Contractor shall conduct concrete placement operations to maintain the
27            differential concrete head as 1'-0" maximum.
28
29       B.   When placing concrete in the dry, only the top five feet of concrete shall be
30            vibrated, in accordance with Section 6-02.3(9), except that the entire depth of
31            concrete placed in the shaft-column steel reinforcing bar splice zone shall be
32            vibrated. If a temporary casing is used it shall be removed before vibration. This
33            requirement may be waived if a temporary casing is used and removed with a
34            vibratory hammer during the concrete placement operation. Vibration of concrete
35            does not affect the maximum slump allowed for the concrete class specified.
36
37       C.   If water is not present, the concrete shall be deposited through the center of the
38            reinforcement cage by a method which prevents segregation of aggregates and
39            splashing of concrete on the reinforcement cage. The concrete shall be placed
40            such that the free-fall is vertical down the center of the shaft without hitting the
41            sides, the steel reinforcing bars, or the steel reinforcing bar cage bracing.
42
43       D.   When placing concrete underwater, including when water in a shaft excavation
44            exceeds three inches in depth with an infiltration rate of 12 inches of depth or more
45            in one hour, the Contractor shall place the concrete by pressure feed using a
46            concrete pump, with a watertight tube having a minimum diameter of 4 inches.
47            The discharge end of the tube on the concrete pump shall include a device to seal
48            out water while the tube is first filled with concrete. Concrete placement by gravity
49            feed is not allowed.
50



     SHAFT.BS1                                    20                           JULY 15, 2010
 1      When the location of the project is at a remote location where it may be difficult to make
 2      arrangements to have a concrete pump at the site, replace subsection 3.07.D with the
 3      following:
 4
 5      D.   When placing concrete underwater, including when water in a shaft excavation
 6           exceeds three inches in depth with an infiltration rate of 12 inches of depth or more
 7           in one hour, the Contractor shall use a concrete pump or tremie. A tremie shall
 8           have a hopper at the top that empties into a watertight tube at least eight inches in
 9           diameter. If a pump is used, a watertight tube shall be used with a minimum
10           diameter of four inches. The discharge end of the tube on the tremie or concrete
11           pump shall include a device to seal out water while the tube is first filled with
12           concrete.
13
14      E.   Throughout the underwater concrete placement operation, the discharge end of the
15           tube shall remain submerged in the concrete at least 5 feet and the tube shall
16           always contain enough concrete to prevent water from entering. The concrete
17           placement shall be continuous until the work is completed, resulting in a seamless,
18           uniform shaft. If the concrete placement operation is interrupted, the Engineer may
19           require the Contractor to prove by core drilling or other tests that the shaft contains
20           no voids or horizontal joints. If testing reveals voids or joints, the Contractor shall
21           repair them or replace the shaft at no expense to the Contracting Agency.
22           Responsibility for coring costs, and calculation of time extension, shall be in
23           accordance with subsection 3.09.H of this Special Provision.
24
25      F.   Before placing any fresh concrete against concrete deposited in water or slurry, the
26           Contractor shall remove all scum, laitance, loose gravel and sediment on the upper
27           surface of the concrete deposited in water or slurry and chip off any high spots on
28           the upper surface of the existing concrete that would prevent the steel reinforcing
29           bar cage from being placed in the position required by the Plans.
30
31           Prior to performing any of the crosshole sonic log testing operations specified in
32           subsection 3.09 of this Special Provision, the Contractor shall remove the concrete
33           at the top of the shaft down to sound concrete.
34
35      G. The Contractor’s construction operation in the vicinity of a shaft excavation with
36         freshly placed concrete and curing concrete shall conform to Section 6-02.3(6)D.
37
38      H.   Except for shafts where the shaft concrete is placed in the dry, the Contractor shall
39           complete a uniform yield form, consistent with the sample form submitted to the
40           Engineer as part of the shaft installation plan as specified in subsection 3.02.B.6 of
41           this Special Provision, for each shaft and shall submit the completed form to the
42           Engineer within 24 hours of completing the concrete placement in the shaft.
43
44      I.   Concrete shall not be placed above the top of shaft (for column splice zones,
45           columns, footings, or shaft caps) until the Contractor receives the Engineer’s
46           acceptance of CSL testing, if performed at that shaft, and acceptance of the shaft.
47
48   3.08 Casing Removal
49




     SHAFT.BS1                                    21                            JULY 15, 2010
 1       A.   As the temporary casing is withdrawn, a minimum 5 foot head of concrete shall be
 2            maintained to balance the foundation material and water pressure at the bottom of
 3            the casing.
 4
 5       B.   Tops of permanent casings for the shafts shall be removed to the top of the shaft
 6            or finished groundline, whichever is lower, unless directed otherwise by the
 7            Engineer. For those shafts constructed within a permanent body of water, tops of
 8            permanent casings for shafts shall be removed to the low water elevation, unless
 9            directed otherwise by the Engineer.
10
11       C.   The Contractor shall completely remove all temporary casings, except as noted.
12            The Contractor may leave some or all of the temporary casing in place provided all
13            the following conditions are satisfied:
14
15                1.   The Contractor shall submit the following information in writing to the
16                     Engineer:
17
18                          a.   The Contractor shall completely describe the portion of the
19                               temporary casing to remain.
20
21                          b.   The Contractor shall specify the reason(s) for leaving the portion
22                               of the temporary casing in place.
23
24                          c.   The Contractor shall submit structural calculations, using the
25                               design specifications and design criteria specified in the General
26                               Notes of the structure Plans, in accordance with Section 6-01.9,
27                               indicating that leaving the temporary casing in place is
28                               compatible with the structure as designed in the Plans.
29
30                2.   The Contractor shall have received the Engineer’s written approval of the
31                     submitted request to leave the temporary casing in place.
32
33   3.09 Nondestructive Testing of Shafts (Crosshole Sonic Log Testing)
34
35       A.   The Contracting Agency will perform crosshole sonic log testing and analysis on all
36            completed shafts designated for testing by the Engineer. The Contracting Agency
37            will require advance notice from the Contractor to schedule all crosshole sonic log
38            testing. The Contractor shall give at least 48 hours notice to the Engineer of the
39            time the concrete in each shaft will be sufficiently cured to allow for crosshole sonic
40            log testing.
41
42            The testing will be performed after the shaft concrete has cured at least 96 hours.
43            Additional curing time prior to testing may be required if the shaft concrete contains
44            admixtures, such as set retarding admixture or water reducing admixture, added in
45            accordance with Section 6-02.3(3). The additional curing time prior to testing
46            required under these circumstances shall not be grounds for additional
47            compensation or extension of time to the Contractor in accordance with Section 1-
48            08.8.
49
50            Crosshole sonic log testing will be conducted at all shafts in which access tubes for
51            test probe access have been installed (see subsection 3.06.A of this Special
52            Provision).

     SHAFT.BS1                                     22                            JULY 15, 2010
 1
 2      If crosshole sonic log testing is to be provided by the Contractor, replace subsection
 3      3.09.A with the following:
 4
 5      A. The Contractor shall provide for crosshole sonic log testing and analysis on all
 6         completed shafts designated for testing by the Engineer. The testing and analysis
 7         shall be performed by the independent testing organization submitted by the
 8         Contractor and approved by the Engineer in accordance with subsection 3.02.D of
 9         this Special Provision.
10
11           The testing shall be performed after the shaft concrete has cured at least 96 hours.
12           Additional curing time prior to testing may be required if the shaft concrete contains
13           admixtures, such as set retarding admixture or water reducing admixture, added in
14           accordance with Section 6-02.3(3). The additional curing time prior to testing
15           required under these circumstances shall not be grounds for additional
16           compensation or extension of time to the Contractor in accordance with Section 1-
17           08.8.
18
19           Crosshole sonic log testing shall be conducted at all shafts in which access tubes
20           for test probe access have been installed (see subsection 3.06.A of this Special
21           Provision).
22
23      B.   After placing the shaft concrete and before beginning the crosshole sonic log
24           testing of a shaft, the Contractor shall inspect the access tubes. Each access tube
25           that the test probe cannot pass through shall be replaced, at the Contractor's
26           expense, with a two inch diameter hole cored through the concrete for the entire
27           length of the shaft. Unless directed otherwise by the Engineer, cored holes shall
28           be located approximately six inches inside the reinforcement and shall not damage
29           the shaft reinforcement. Descriptions of inclusions and voids in cored holes shall
30           be logged and a copy of the log shall be submitted to the Engineer. Findings from
31           cored holes shall be preserved, identified as to location, and made available for
32           inspection by the Engineer.
33
34      C.   The Engineer will determine final acceptance of each shaft, based on the crosshole
35           sonic log test results and analysis for the tested shafts, and will provide a response
36           to the Contractor within three working days after receiving the test results and
37           analysis submittal.
38
39      If crosshole sonic log testing is to be provided by the Contractor, replace subsection
40      3.09.C with the following:
41
42      C.   The Contractor shall submit the results and analysis of the crosshole sonic log
43           testing for each shaft tested to the Engineer for approval. The Engineer will
44           determine final acceptance of each shaft, based on the crosshole sonic log test
45           results and analysis for the tested shafts, and will provide a response to the
46           Contractor within three working days after receiving the test results and analysis
47           submittal.
48
49      D.   Except as otherwise noted, the Contractor shall not commence subsequent shaft
50           excavations until receiving the Engineer's approval and acceptance of the first
51           shaft, based on the results and analysis of the crosshole sonic log testing for the

     SHAFT.BS1                                    23                           JULY 15, 2010
 1           first shaft. The Contractor may commence subsequent shaft excavations prior to
 2           receiving the Engineer’s approval and acceptance of the first shaft, provided the
 3           following condition is satisfied:
 4
 5               1.   The Engineer approves continuing with shaft construction based on the
 6                    Engineer’s observations of the construction of the first shaft, including, but
 7                    not limited to, conformance to the shaft installation plan as approved by
 8                    the Engineer, and the Engineer’s review of Contractor’s daily reports and
 9                    Inspector’s daily logs concerning excavation, steel reinforcing bar
10                    placement, and concrete placement.
11
12      E.   If the Contractor requests, the Engineer may direct that additional testing be
13           performed at a shaft. If subsequent testing at a shaft indicates the presence of a
14           defect(s) in the shaft, the testing costs and the delay costs resulting from the
15           additional testing shall be borne by the Contractor in accordance with Section 1-
16           05.6. If this additional testing indicates that the shaft has no defect, the testing
17           costs and the delay costs resulting from the additional testing will be paid by the
18           Contracting Agency in accordance with Section 1-05.6, and, if the shaft
19           construction is on the critical path of the Contractor’s schedule, a time extension
20           equal to the delay created by the additional testing will be granted in accordance
21           with Section 1-08.8.
22
23      F.   For all shafts determined to be unacceptable, the Contractor shall submit a plan for
24           further investigation or remedial action to the Engineer for approval.           All
25           modifications to the dimensions of the shafts, as shown in the Plans, required by
26           the investigation and remedial action plan shall be supported by calculations and
27           working drawings as specified in Section 6-01.9. All investigation and remedial
28           correction procedures and designs shall be submitted to the Engineer for approval.
29           The Contractor shall not begin repair operations until receiving the Engineer's
30           approval of the investigation and remedial action plan.
31
32      G. If the Engineer determines that the concrete placed under slurry for a given shaft is
33         structurally inadequate, that shaft will be rejected. The placement of concrete
34         under slurry shall be suspended until the Contractor submits to the Engineer
35         written changes to the methods of shaft construction needed to prevent future
36         structurally inadequate shafts, and receives the Engineer's written approval of the
37         submittal.
38
39      H.   At the Engineer's request, the Contractor shall drill a corehole in any questionable
40           quality shaft (as determined from crosshole sonic log testing and analysis or by
41           observation of the Engineer) to explore the shaft condition.
42
43           Prior to beginning coring, the Contractor shall submit the method and equipment
44           used to drill and remove cores from shaft concrete to the Engineer and receives
45           the Engineer’s written approval. The coring method and equipment shall provide
46           for complete core recovery and shall minimize abrasion and erosion of the core.
47
48           If a defect is confirmed, the Contractor shall pay for all coring costs in accordance
49           with Section 1-05.6. If no defect is encountered, the Contracting Agency will pay
50           for all coring costs in accordance with Section 1-05.6, and, if the shaft construction
51           is on the critical path of the Contractor’s schedule, compensation for the delay will
52           be granted by an appropriate time extension in accordance with Section 1-08.8.

     SHAFT.BS1                                    24                            JULY 15, 2010
 1           Materials and work necessary, including engineering analysis and redesign, to
 2           effect corrections for shaft defects shall be furnished to the Engineer's satisfaction
 3           at no additional cost to the Contracting Agency.
 4
 5      I.   All access tubes and cored holes shall be dewatered and filled with grout after tests
 6           are completed. The access tubes and cored holes shall be filled using grout tubes
 7           that extend to the bottom of the tube or hole or into the grout already placed.
 8
 9   Measurement
10   4.01 Measurement
11
12      A.   Measurement will be made as follows:
13
14           1.   Soil excavation for shaft including haul will be measured by the cubic yards of
15                shaft excavated. The cubic yards will be computed using the shaft diameter
16                shown in the Plans, the top of shaft soil excavation, as defined below, and the
17                bottom elevation shown in the Plans, unless adjusted by the Engineer, less all
18                rock excavation measured as specified in item 2.
19
20                Except as otherwise specified, the top of shaft soil excavation shall be defined
21                as the highest existing ground point within the shaft diameter. For shafts
22                where the top of shaft is above the existing ground line and where the Plans
23                show embankment fill placed above the existing ground line to the top of shaft
24                and above, the top of shaft soil excavation shall be defined as the top of shaft.
25                Excavation through embankment fill placed above the top of shaft will not be
26                included in the measurement.
27
28           2.   Rock excavation for shaft including haul will be measured by the cubic yards of
29                shaft excavated. The cubic yards will be computed using the shaft diameter
30                shown in the Plans, the top of the rock line, defined as the highest bedrock
31                point within the shaft diameter, and the bottom elevation shown in the Plans,
32                unless adjusted by the Engineer.
33
34           3.   Furnishing and placing temporary casing will be measured by the number of
35                linear feet of required temporary casing, as specified in subsection 3.03.B of
36                this Special Provision, installed within the limits shown in the Plans, plus
37                additional length approved by the Engineer for temporary casing required to
38                address field conditions as encountered.
39
40           4.   Furnishing permanent casing will be measured by the number of linear feet of
41                required permanent casing, as specified in subsection 3.03.B of this Special
42                Provision, installed below the cutoff elevation.
43
44           5.   Placing permanent casing will be measured by the number of permanent
45                casings placed.
46
47           6.   Casing shoring will be measured by the number of linear feet of casing shoring
48                installed. The linear feet dimension will be computed using either the top of
49                ground line, defined as the highest ground line elevation within the casing
50                shoring, or the specified shaft seal vent elevation as shown in the Plans,
51                whichever is higher, and the bottom elevation as shown in the Plans.
52

     SHAFT.BS1                                    25                           JULY 15, 2010
 1           7.   Concrete Class 4000P for shaft will be measured by the cubic yards of
 2                concrete in place. The cubic yards will be computed using the shaft diameter
 3                shown in the Plans, and the top and bottom elevations shown in the Plans,
 4                unless adjusted by the Engineer.
 5
 6           8.   Steel reinforcing bar for shaft will be measured by the computed weight of all
 7                reinforcing steel in place, as shown in the Plans. Bracing for steel reinforcing
 8                bar cages shall be considered incidental to this item of work.
 9
10           9.   CSL access tube will be measured by the linear foot of tube furnished and
11                installed.
12
13           When the Contract requires a minimum penetration into a bearing layer, as
14           opposed to a specified shaft tip elevation, and the bearing layer elevation at each
15           shaft cannot be accurately determined, replace subsections 4.01.A.8 and 4.01.A.9
16           with the following:
17
18           8. Steel reinforcing bar for shaft will be measured by the computed weight of all
19           the steel reinforcing bar for the shaft to the design depth shown in the Plans plus
20           the weight required to extend the shaft reinforcement by 20 percent in length as
21           specified in subsection 3.05.E of this Special Provision. Bracing for steel
22           reinforcing bar cages shall be considered incidental to this item of work.
23
24           9.   CSL access tube will be measured by the linear foot of tube required based on
25                the design depth shown in the Plans plus the length required to extend the
26                shaft reinforcement by 20 percent in length as specified in subsection 3.05.E
27                of this Special Provision.
28
29
30           If crosshole sonic log testing is to be provided by the Contractor, add the following
31           subsection:
32
33           10. CSL test will be measured once per shaft tested.
34
35           For projects with shafts constructed in salt water when the geotechnical report
36           specifies that the use of fresh water for synthetic slurry is feasible and when the
37           Contracting Agency wishes to restrict the water for synthetic slurry to fresh water
38           only, add the following subsection at the end of subsection A:
39
40           11. Fresh water for shaft slurry will be measured in accordance with Section 2-
41               07.4.
42
43   Payment
44   5.01 Payment
45
46      A.   Payment will be made, in accordance with Section 1-04.1, for the following bid
47           items when they are included in the proposal:
48
49                1.   "Soil Excavation For Shaft Including Haul", per cubic yard, including all
50                     costs in connection with furnishing, mixing, placing, maintaining,


     SHAFT.BS1                                   26                           JULY 15, 2010
 1                     containing, collecting, and disposing of all mineral, synthetic, and water
 2                     slurry, and disposing of ground water collected by the shaft excavation.
 3
 4                2.   "Rock Excavation For Shaft Including Haul", per cubic yard.
 5
 6                3.   "Furnishing & Placing Temp. Casing For _____ Dia. Shaft", per linear
 7                     foot, including all costs in connection with completely removing the casing
 8                     after completing shaft construction.
 9
10                4.   "Furnishing Permanent Casing For ____ Diam. Shaft", per linear foot.
11
12                5.   "Placing Permanent Casing For _____ Diam. Shaft", per each.
13
14                6.   “Casing Shoring”, per linear foot, including all costs in connection with
15                     placing seals when required.
16
17                7.   "Shoring Or Extra Excavation Cl. A - _____", lump sum, including all costs
18                     in connection with all excavation outside the limits specified for items 1
19                     and 2, all temporary telescoping casings, and all temporary casings not
20                     included in the measurement for required temporary casing in accordance
21                     with subsection 4.01.A.3 as specified in this Special Provision.
22
23                8.   "Conc. Class 4000P For Shaft", per cubic yard.
24
25                9.   "St. Reinf. Bar For Shaft", per pound, including all costs in connection with
26                     furnishing and installing steel reinforcing bar centralizers.
27
28                10. "CSL Access Tube", per linear foot.
29
30                If crosshole sonic log testing is to be provided by the Contractor, add the
31                following subsection, and renumber subsection 5.01.A.11 to 5.01.A.12:
32
33                11. "CSL Test", per each shaft tested.
34
35                11. "Removing Shaft Obstructions", estimated.
36
37                For projects with shafts constructed in salt water when the geotechnical report
38                specifies that the use of fresh water for synthetic slurry is feasible and when
39                the Contracting Agency wishes to restrict the water for synthetic slurry to fresh
40                water only, add the following subsection at the end of subsection A:
41
42                12. "Fresh Water For Shaft Slurry", per M gal.
43
44      B.   Payment for Removing Shaft Obstructions
45
46           1.   Payment for removing, breaking-up, or pushing aside, shaft obstructions, as
47                defined in subsection 3.03.G of this Special Provision, will be made for the
48                changes in shaft construction methods necessary to deal with the obstruction.
49                The Contractor and the Engineer shall evaluate the effort made and reach
50                agreement on the equipment and employees utilized, and the number of hours
51                involved for each. Once these cost items and their duration have been agreed

     SHAFT.BS1                                    27                            JULY 15, 2010
 1               upon, the payment amount will be determined using the rate and markup
 2               methods specified in Section 1-09.6. For the purpose of providing a common
 3               proposal for all bidders, the Contracting Agency has entered an amount for the
 4               item "Removing Shaft Obstructions" in the bid proposal to become a part of
 5               the total bid by the Contractor.
 6
 7         2.    If shaft construction equipment is idled as a result of the work required to deal
 8               with the obstruction and cannot be reasonably reassigned within the project,
 9               then standby payment for the idled equipment will be added to the payment
10               calculations. If labor is idled as a result of the work required to deal with the
11               obstruction and cannot be reasonably reassigned within the project, than all
12               labor costs resulting from Contractor labor agreements and established
13               Contractor policies will be added to the payment calculations.
14
15         3.    The Contractor shall perform the amount of obstruction work estimated by the
16               Contracting Agency within the original time of the contract. The Engineer will
17               consider a time adjustment and additional compensation for costs related to
18               the extended duration of the shaft construction operations, provided:
19
20                   a.   the dollar amount estimated by the Contracting Agency has been
21                        exceeded, and
22
23                   b.   the Contractor shows that the obstruction removal work represents a
24                        delay to the completion of the project based on the current progress
25                        schedule provided in accordance with Section 1-08.3.




     SHAFT.BS1                                   28                           JULY 15, 2010

								
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