SECTION DRILLED CONCRETE PIERS AND SHAFTS

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1 SECTION PART 1 - GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section. 1.2 SUMMARY A. This Section includes the following: 1. Drilling, casing (if necessary), cleaning, and dewatering (if necessary) of drilled pier holes. 2. Removal of drilling spoil from immediate vicinity of the drilled pier hole. 3. Forming shear rings. Roughing of pier hole sides. 4. Installation of concrete and reinforcing in drilled piers. 5. All other work normally related to the above or specified under this section. B. Related Sections include the following: 1. Division 01 Section "Unit Prices" for list of unit prices. 2. Division 01 Section "Temporary Facilities and Controls." 3. Division 03 Section "Cast-in-Place Concrete" for general structural and building applications of concrete. C. Work Installed but Furnished under Other Sections. 1. Drilled Pier Reinforcing and Dowels: Furnished under Division 3 Section Cast-in-Place Concrete. 2. Concrete for Drilled Pier: Furnished under Division 3 Section Cast-in-Place Concrete. 3. Concrete Testing: Division 3 Section Cast-in-Place Concrete. 4. Anchor Rods: Furnished under Division 5 Section for Structural Steel. 1.3 UNIT PRICES A. Basis of Bids: Base bids on indicated number of drilled piers; design length from top elevation to bottom of shaft, and diameter of shaft. B. Basis for Payment: Payment for drilled piers will be made on actual net volume of drilled piers in place and approved. Actual length and shaft diameter may vary to coincide with elevations where satisfactory bearing strata are encountered, and with actual bearing value of bearing strata determined by an independent testing and inspecting agency. Adjustments will be made on net variation of total quantities, based on design dimensions for shafts. 1. Unit prices include labor, materials, tools, equipment, and incidentals required for excavation, trimming, shoring, casings, dewatering, reinforcement, concrete fill, and other items for complete drilled-pier installation

2 2. See Division 01 Section "Unit Prices" for unit of measurement. 1.4 SUBMITTALS A. Product Data: For each type of product indicated. B. Shop Drawings: For concrete reinforcement detailing fabricating, bending, and placing. C. Design Mixes: For each class of concrete. Include revised mix proportions when characteristics of materials, Project conditions, weather, test results, or other circumstances warrant adjustments. 1. Laboratory Test Reports: For evaluation of concrete materials and mix design. D. Qualification Data: For Installer and surveyor. E. Record drawings at Project closeout according to Division 01 Section "Closeout Procedures." 1.5 QUALITY ASSURANCE A. Drilled-Pier Standard: Comply with provisions in ACI 336.1, "Reference Specifications for the Construction of Drilled Piers," unless modified in this Section. B. Survey Work: Engage a qualified land surveyor or professional engineer to perform surveys, layouts, and measurements for drilled piers. Before excavating, lay out each drilled pier to lines and levels required. Record actual measurements of each drilled pier's location, shaft diameter, bottom and top elevations, deviations from specified tolerances, and other specified data. 1. Record and maintain information pertinent to each drilled pier and cooperate with Owner's testing and inspecting agency to provide data for required reports. C. Testing Agency Qualifications: Qualified according to ASTM C 1077 and ASTM E 329 to perform material evaluation tests selected and paid for by the Owner. 1. Contractor shall furnish Testing Agency access to work, facilities, and incidental labor required for testing and inspection. Retention by the Owner of an independent Testing Agency shall in no way relieve the Contractor of responsibility for performing all work in accordance with the contract requirements. See requirements herein for Testing Agency services. 2. The Owner s Testing and Inspection Agency shall be the Project Geotechnical Engineer where indicated. D. Pre-installation Conference: Conduct conference at Project site to comply with requirements in Division 01 Section "Project Management and Coordination." 1.6 PROJECT CONDITIONS A. Existing Utilities: Locate existing underground utilities before excavating drilled piers. If utilities are to remain in place, provide protection from damage during drilled-pier operations

3 1. Should uncharted or incorrectly charted piping or other utilities be encountered during excavation, adapt drilling procedure if necessary to prevent damage to utilities. Cooperate with Owner and utility companies in keeping services and facilities in operation without interruption. Repair damaged utilities to satisfaction of utility owner. B. Site Information: A geotechnical report has been prepared for this Project. Copies of the report may be obtained from the office of the Owner. 1. The drilling log and accompanying report are believed to be accurate; however, neither the Owner, Architect, nor the Structural Engineer guarantees the information contained nor do they guarantee the conditions indicated to exist at the location of the test holes will prevail at other locations on the site. PART 2 - PRODUCTS 2.1 STEEL REINFORCEMENT A. Meet requirements of Section Cast-in-Place Structural Concrete. 2.2 CONCRETE MATERIALS A. Meet requirements of Section Cast-in-Place Structural Concrete. 2.3 STEEL CASINGS A. Steel Pipe Casings: ASTM A 283/A 283M, Grade C; or ASTM A 36/A 36M, carbon-steel plate, with joints full-penetration welded according to AWS D Provide casings where required of sufficient strength to withstand handling stresses, concrete pressure and surrounding earth pressure. Casing inside diameter shall equal size of drilled pier specified such that the drilled pier diameter is within the tolerances noted below. PART 3 - EXECUTION 3.1 PREPARATION A. Protect structures, utilities, sidewalks, pavements, and other facilities from damage caused by settlement, lateral movement, vibration, and other hazards created by drilled-pier operations. 3.2 EXCAVATION A. Drilling: By personnel experienced and properly equipped to construct drilled piers of indicated diameter and length. Drill diameter and with penetration into bearing material as indicated or as directed by the on-site Project Geotechnical Engineer

4 B. Unclassified Excavation: Excavation is unclassified and includes excavation to bearing elevations regardless of character of materials or obstructions encountered. 1. Unclassified excavation includes removal of unanticipated boulders, concrete, masonry, or other subsurface obstructions. 2. Removal of unanticipated boulders, concrete, masonry, or other unforeseen obstructions that cannot be removed by conventional augers fitted with soil or rock teeth, drilling buckets, or underreaming tools attached to drilling equipment of size, power, torque, and downthrust necessary for the Work, will be paid according to Contract provisions for changes in the Work. C. Prevent surface water from entering excavated shafts. Conduct water to site drainage facilities. D. Excavate shafts for drilled piers to indicated elevations. Remove loose material from bottom of excavation. 1. Excavate bottom of drilled piers to level plane within 1:12 tolerance. 2. Cleaning and Dewatering: Holes shall be thoroughly dewatered and cleaned of debris by the Contractor before placing concrete. The Contractor shall provide pumps in operating condition, of proper type and capacity for this type of work and sufficient hose to carry water away from excavations. Holes shall be dewatered so no more than 3 inches of water exists in the bottom of any hole when placing of concrete is started. Necessary equipment for cleaning of holes and a back-up pump in operating condition for dewatering shall be available on site at all times. 3. Cut series of grooves about perimeter of shaft to height from bottom of shaft, vertical spacing and dimensions indicated. Roughen sides of drilled pier hole as directed by Project Geotechnical Engineer. E. Notify and allow Project Geotechnical Engineer to test and inspect bottom of excavation. If unsuitable bearing stratum is encountered, make adjustments to drilled piers as determined by Architect. 1. Do not excavate shafts deeper than elevations indicated, unless approved by Architect. 2. Additional authorized excavation will be paid according to Contract provisions for changes in the Work. F. Excavate shafts for closely spaced drilled piers and those occurring in fragile or sand strata, only after adjacent drilled piers are filled with concrete and allowed to set. G. Temporary Casings: Where necessary, install watertight steel casings of sufficient length and thickness to prevent entry of soil or water seepage into shaft; to withstand compressive, displacement, and withdrawal stresses; and to maintain stability of shaft walls. The use of mud slurry to lubricate casings or seal off water will be allowable only with the prior approval of the Project Geotechnical and Structural Engineers. Casings may be left in place only with prior approval of the Project Geotechnical and Structural Engineers. 1. Casing Removal: Pull temporary casing with a slow and smooth vertical motion maintaining casing in a plumb position. Casing shall not be pulled until concrete has been placed to a minimum of 5 feet above external water or slurry level or level of unstable soil. During pulling maintain concrete level a minimum of 5 feet above bottom of casing. Vibrate top 5 feet of pier after temporary casing is removed. H. Tolerances: Construct drilled piers to remain within ACI tolerances

5 1. If location or out-of-plumb tolerances are exceeded, provide corrective construction. Submit design and construction proposals to Architect for review before proceeding. I. Inspection: Each drilled pier must be inspected by the Project Geotechnical Engineer before placing concrete. 1. Provide and maintain facilities with equipment required for testing and inspecting excavations. Cooperate with testing and inspecting personnel to expedite the Work. 2. Notify Architect and Project Geotechnical Engineer at least six hours before excavations are ready for tests and inspections. 3.3 STEEL REINFORCEMENT A. Comply with recommendations in CRSI's "Manual of Standard Practice" for fabricating, placing, and supporting reinforcement. 1. Reinforcing: Exact location of dowels and reinforcing extending into adjacent construction shall be verified by the Contractor. Deviations in location of such reinforcing in excess of specified placing tolerances shall be reported to the Architect and Structural Engineer within 24 hours after concrete is placed. In reinforced piers, completed installation of reinforcement must be approved by the Project Geotechnical Engineer before depositing concrete. B. Clean reinforcement of loose rust and mill scale, earth, and other materials that reduce or destroy bond with concrete. C. Fabricate and install reinforcing cages symmetrically about axis of shafts in a single unit. D. Accurately position, support, and secure reinforcement against displacement during concreting. Maintain minimum cover to reinforcement. E. Use templates to set anchor bolts, leveling plates, and other accessories furnished in work of other Sections. Provide blocking and holding devices to maintain required position during final concrete placement. F. Protect exposed ends of extended reinforcement, dowels, or anchor bolts from mechanical damage and exposure to weather. 3.4 CONCRETE PLACEMENT A. Place concrete in continuous operation and without segregation immediately after inspection and approval of shaft by the Project Geotechnical Engineer. 1. Place concrete continuously without construction joints for full height of pier. 2. Construct a construction joint if concrete placement is delayed more than one hour. Level top surface of concrete. Before placing remainder of concrete, clean surface laitance, roughen, and slush concrete with commercial bonding agent or with sandcement grout mixed at ratio of 1:1. B. Place concrete to fall vertically down the center of drilled pier without striking sides of shaft or steel reinforcement

6 1. Where concrete cannot be directed down shaft without striking reinforcing, place concrete with chutes, tremies, or pumps. For 24 inch and smaller diameters, free fall of vertical concrete shall not exceed 20 feet. 2. Vibrate top 60 inches of concrete after dowels or anchor bolts have been placed. 3. Do not deposit concrete in more than three inches of water. C. Screed concrete at cutoff elevation level and apply scoured, rough finish. Where cutoff elevation is above the ground elevation, form top section above grade and extend shaft to required elevation. Enlargement or mushrooming of top part of drilled pier is not permitted. D. Protect concrete work, according to ACI 301, from frost, freezing, or low temperatures that could cause physical damage or reduced strength. 1. Do not use frozen materials or materials containing ice or snow. Do not place concrete on frozen subgrade or on subgrade containing frozen materials. 2. Do not use calcium chloride, salt, or other mineral-containing antifreeze agents or chemical accelerators. E. When hot-weather conditions exist that would seriously impair quality and strength of concrete, place concrete according to ACI 301 to maintain delivered temperature of concrete at no greater than 90 deg F. 3.5 FIELD QUALITY CONTROL A. Testing Agency: Owner will engage a qualified independent testing and inspecting agency and the Project Geotechnical Engineer to sample materials, perform tests, and submit reports during excavation and concrete placement for drilled piers. B. A drilled-pier report will be prepared by the Project Soils Geotechnical Engineer for each drilled pier as follows: 1. Identification Mark. 2. Shaft diameter. 3. Actual top and bottom elevations, and design bottom elevation. 4. Top of bearing strata elevation. 5. Description of soil materials. 6. Description, location, and dimensions of obstructions. 7. Final top centerline location and deviations from requirements. 8. Variation of shaft from plumb. 9. Shaft excavating method. 10. Levelness of bottom and adequacy of cleanout. 11. Ground-water conditions and water-infiltration rate, depth, and pumping. 12. Description, diameter, and top and bottom elevations of temporary casings. Include elevation of top of concrete, elevation of bottom of casing and elevation of external water level immediately before casing is pulled. 13. Description of soil or water movement, sidewall stability, loss of ground, and means of control. 14. Date and time of starting and completing excavation. 15. Size, number, and position of reinforcing steel. 16. Concrete placing method, including elevation of consolidation and delays. 17. Elevation of concrete during removal of casings. 18. Locations of construction joints. 19. Remarks, unusual conditions encountered, and deviations from requirements

7 20. Concrete testing results. 21. Overrun or underrun. C. Soil Testing: Bottom elevations, bearing capacities, and lengths of drilled piers indicated have been estimated from available soil data. Actual elevations and drilled-pier lengths will be determined by the Project Geotechnical Engineer. Final evaluations and approval of data will be determined by Architect. D. The Testing Agency shall test concrete as specified in Section Cast-in-Place Structural Concrete. Take test specimens, consisting of at least one set of four cylinders as follows: 1. If more than one pier is cast from the same truckload, take one set per truckload. 2. If more than one truckload is placed in a pier, take one set per pier. 3.6 DISPOSAL OF MATERIALS A. Material removed during drilled pier construction shall not be used for fill. Remove surplus excavated material and slurry and legally dispose of it off Owner's property. Dispose of such material as specified under Section Earthwork. END OF SECTION

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