Attachment 2 - Addendum 02.pdf

Addendum No. 02

Date: December 15, 2021

Project: Remodel Front Entrance

Project #: 539-21-211

Location: Cincinnati VA Medical Center

3200 Vine Street

Cincinnati, OH 45220

This Addendum supplements and amends the original Drawings and Specifications for the above referenced project. This Addendum shall be forwarded to all Prime Bidders and all appropriate building code authorities. This Addendum shall be taken into account in the preparation of bids and shall become a part of the Contract Documents.

Receipt of this Addendum must be acknowledged on the Bid Form.

This addendum consists of the following items:

The following structural revisions to the drawings and specifications is in response to RFI’s submitted during the bidding process. The drilled caisson spec has been added to the project as well as the note removed from the canopy column / pier detail on sheet S101 stating that all shafts must be tested for gas before entering.

Drawings

1. Sheet S101: Foundation Plan

a. Note for shafts to be tested for gas before entering on the Typical

Canopy Column / Drilled Pier Detail has been removed. Revision clouded in.

Specifications

1. Section 00 01 10: Table of Contents

a. Section 31 63 26 Drilled Caissons has been added to the project specifications Table of Contents. Revision clouded in.

2. Section 31 63 26: Drilled Caissons

a. Entire section has been added to construction specifications

End of Addendum No. 02

SOCKET 10'-0" INTO

GLACIAL TILL.

PIER CAP 42"X42"X36"

DEEP (-10").

15'-2" 12'-6"

'-2

'-6

36" DIA

T/CAP=727'-2"

B/PIER=695'-2"

36" DIA

T/CAP=727'-2"

B/PIER=695'-2"

36" DIA

T/CAP=727'-2"

B/PIER=695'-2"

36" DIA

T/CAP=727'-2"

B/PIER=695'-2"

36" DIA

T/CAP=727'-2"

B/PIER=695'-2"

DRILLED PIER SCHEDULE

PIERS TO EXTEND A MINIMUM OF 10'-0" INTO

GLACIAL TILL UNLESS NOTED OTHERWISE.

CAST BOXOUT AFTER CANOPY

COLUMN IS PLUMB AND GROUTED.

#4 TIE.

1/2" ISOLATION JOINT FULL DEPTH OF SLAB

ALL AROUND BOXOUT.

6 SETS OF DRILLED PIER TIES (3 TIES AT 3" TOP)

IN UPPER SEGMENT.

CONSTRUCTION JOINT

DRILLED PIER REINFORCEMENT PER SCHEDULE.

MINIMUM OF 4 BARS SHALL EXTEND TO BOTTOM OF

SHAFT TO SUPPORT THE CAGE. FABRICATE THESE

BARS 3'-0" LONGER THAN DESIGN LENGTH AND CUT

IN FIELD. REMAINDER OF VERTICAL BARS MAY STOP

AT DESIGN DEPTH. TIES REQUIRED FULL LENGTH OF

PIER. PROVIDE (2) ADDITIONAL TIES TO

ACCOMMODATE UP TO 3'-0" SHAFT EXTENSION.

REFER TO FOUNDATION PLAN FOR ESTIMATED

BOTTOM OF PIER ELEVATION. ELEVATIONS SHOWN

ARE FOR BIDDING PURPOSES ONLY. RAISE OR LOWER

ELEVATIONS IN FIELD AS DIRECTED BY GEOTECHNICAL

ENGINEER.

FORM UPPER SEGMENT OF PIER AS REQUIRED

AND ANY PORTION OF PIER WHICH PROJECTS

ABOVE SUBGRADE. UPPER SEGMENT SQUARE.

TYPICAL CANOPY COLUMN/DRILLED PIER

STAGGER LAPS AND HOOKS ON OPPOSITE SIDES

OF PIER.

NOTES:

1. CENTER DRILLED PIERS BELOW COLUMNS UNLESS NOTED OTHERWISE.

SIZE VERTICAL BARS TIES

36" DIA (9) #7 #4 AT 18"

CIRCULAR COLUMN BOXOUT,

CAST SEPARATE OF SLAB.

2" MIN. AT CORNER OF BASE PLATE

SLAB ON GRADE

TOP OF DRILLED PIER

BOTTOM OF DRILLED PIER

SHAFT DIAMETER

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COLUMN BY CANOPY MANUFACTURE.

PROVIDE ANCHOR BOLTS PER CANOPY

MANUFACTURERS DRAWINGS.

3131 Newmark Drive, Suite 200 Miamisburg, Ohio 45342 |www.johnpoe.com| 937.461.3290

VA Project No.

JPA Project No.

Project Number

Building Number

Drawing Number

Project Title

Location

Issue Date Checked Drawn

Drawing Title

Approved:

VA FORM 08 - 6231

A

FULLY SPRINKLERED

U.S. Department of Veterans Affairs

B

C

D

E

F

A

B

C

D

E

F

21 4 5 6 7 8 9 10

PhaseARCHITECT/ENGINEER OF RECORD STAMPCONSULTANT

321 4 5 6 7 8 9 10

/1

5/

2:

:1

PM

Remodel Front Entrance

7/9/2021

FOUNDATION PLAN

S101

JTBFJE

20005.00 539-21-211

Cincinnati VAMC

B1

100% SUBMITTAL

1/4" = 1'-0"S101

1 LEVEL 1 FOUNDATION PLAN

NORTH

Revisions Date

1 ADDENDUM 2 12/15/2021

539-21-211 TABLE OF CONTENTS

Remodel Front Entrance 01-21 VAMC Cincinnati, OH

00 01 10-1

DEPARTMENT OF VETERANS AFFAIRS

VHA MASTER SPECIFICATIONS

TABLE OF CONTENTS

Section 00 01 10

SECTION NO. DIVISION AND SECTION TITLES DATE

DIVISION 00 - SPECIAL SECTIONS

00 01 15 List of Drawing Sheets 05-20

DIVISION 01 - GENERAL REQUIREMENTS

01 00 00 General Requirements 01-21

01 32 16.15 Project Schedules (Small Projects – Design/Bid/Build 03-20

01 33 23 Shop Drawings, Product Data, and Samples 05-17

01 35 26 Safety Requirements 07-20

01 42 19 Reference Standards 11-20

01 45 00 Quality Control 02-21

01 45 29 Testing Laboratory Services 11-18

01 57 19 Temporary Environmental Controls 01-21

01 58 16 Temporary Interior Signage 07-15

01 74 19 Construction Waste Management 01-21

01 81 13 Sustainable Construction Requirements 10-17

DIVISION 02 – EXISTING CONDITIONS

02 41 00 Demolition 08-17

02 65 00 Underground Storage Tank Removal 01-21

02 82 13.19 Asbestos Floor Tile and Mastic Abatement 01-21

DIVISION 03 – CONCRETE

03 30 53 (Short-Form) Cast-in-Place Concrete 01-21

DIVISION 04 – MASONRY – N/A

DIVISION 05 – METALS – N/A

DIVISION 06 – WOOD, PLASTICS AND COMPOSITES

06 10 00 Rough Carpentry 10-17

DIVISION 07 - THERMAL AND MOISTURE PROTECTION

07 60 00 Flashing and Sheet Metal 01-21

07 84 00 Firestopping 01-21

07 92 00 Joint Sealants 10-17

DIVISION 08 - OPENINGS

00 01 10-2

08 41 13 Aluminum-Framed Entrances and Storefronts 01-21

08 42 33 Revolving Door Entrances 01-21

08 71 00 Door Hardware 01-21

08 71 13.11 Low Energy Power Assist Door Operators 01-21

08 80 00 Glazing 01-21

DIVISION 09 – FINISHES

09 22 16 Non-Structural Metal Framing 06-18

09 29 00 Gypsum Board 04-20

09 68 00 Carpeting 01-21

09 91 00 Painting 01-21

DIVISION 10 – SPECIALTIES

10 14 00 Signage 01-21

10 73 00 Translucent Fiberglass Sandwich Panel Open Canopy System 11-15

DIVISION 11 – EQUIPMENT

DIVISION 12 – FURNISHINGS

DIVISION 13 - SPECIAL CONSTRUCTION

DIVISION 14– CONVEYING EQUIPEMENT

DIVISION 21- FIRE SUPPRESSION

DIVISION 22 – PLUMBING

DIVISION 23 – HEATING, VENTILATING, AND AIR CONDITIONING

(HVAC)

DIVISION 25 – INTEGRATED AUTOMATION

DIVISION 26 – ELECTRICAL

26 05 11 Requirements for Electrical Installations 01-16

26 05 19 Low-Voltage Electrical Power Conductors and Cables 01-17

26 05 26 Grounding and Bonding for Electrical Systems 01-17

26 05 33 Raceway and Boxes for Electrical Systems 01-18

26 05 41 Underground Electrical Construction 01-17

26 09 23 Lighting Controls 01-18

26 27 26 Wiring Devices 01-18

26 56 00 Exterior Lighting 01-18

DIVISION 27 – COMMUNICATIONS

DIVISION 28 – ELECTRONIC SAFETY AND SECURITY

00 01 10-3

DIVISION 31 – EARTHWORK

31 20 11 Earthwork (Short Form) 10-12

31 63 26 Drilled Caissons 10-12

DIVISION 32 – EXTERIOR IMPROVEMENTS

32 05 23 Cement and Concrete for Exterior Improvements 08-16

32 12 16 Asphalt Paving 09-15

32 31 13 Chain Link Fences and Gates 06-18

DIVISION 33 – UTILITIES

33 40 00 Storm Sewer Utilities 12-17

DIVISION 34 – TRANSPORTATION

34 71 13 Passive Vehicle Barriers 04-18 cvaughn Cloud

SECTION 31 63 26

DRILLED CAISSONS

PART 1 - GENERAL

1.1 DESCRIPTION

This section specifies excavation and concrete required for construction of foundation caissons.

1.2 DEFINITIONS

Satisfactory Bearing Material: ten foot into Glacial Till and is assumed to occur at bottom of caisson elevations shown.

1.3 RELATED WORK

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

SERVICES.

B. Safety requirements and blasting operations: Section 00 72 00, GENERAL CONDITIONS, Article, ACCIDENT PREVENTION.

C. Subsurface Investigation: Section 01 00 00, GENERAL REQUIREMENTS, Article, PHYSICAL

DATA

D. Earth excavation: Section 31 20 00, EARTH MOVING.

E. Concrete, including materials and mixes: Section 03 30 50, CAST-IN-PLACE CONCRETE.

1.4 CONTRACT BASIS

A. Contract price for caissons will be based upon total length for each type of caisson shown and number of caisson load tests indicated in the Contract Documents. Length of caissons will be measured from bottom elevation to top elevation of the caisson. The diameter of the caisson is defined as the minimum diameter of the shaft.

1. Adjustment of contract price shall be based upon total length of each type of caisson placed and not on the length of individual caissons. When the total length of each type of completed caisson is greater or less than the length shown due to unsuitable soils or design modifications by the COR, contract price adjustment will be made in accordance with Articles, DIFFERING SITE CONDITIONS, CHANGES and CHANGES-SUPPLEMENT of the

GENERAL CONDITIONS as applicable.

2. Contract price and time will be adjusted in accordance with Articles, DIFFERING SITE

CONDITIONS, CHANGES and CHANGES-SUPPLEMENT of the GENERAL CONDITIONS as applicable, when artificial materials that are not shown are encountered.

1.5 CLASSIFICATION OF EXCAVATION

A. Soil/Weathered Rock Excavation:

Soil or weathered rock that can be reasonably excavated with the rock auger, i.e. rock auger advancement greater than 6 inches per 15 minutes (see rock auger refusal, 1.5.C-2, below)

539-21-211 DRILLED CAISSONS

Remodel Front Entrance 10-12

31 63 26 - 2

B. Sloping Weathered Rock Excavation:

Excavation of soil/weathered rock that can typically be excavated with the rock auger, except when the steeply sloping orientation of the stratum causes the rock auger to run askew.

C. Rock Excavation:

1. Excavation of material that meets the rock auger refusal criteria and requires the rock core barrel or other hard rock excavation techniques for removal.

2. Rock auger refusal is defined as a penetration rate of less than 6 inches in 15 minutes, while operating a caisson drilling rig, rated with a torque capacity of at least 1,000,000 inch-pounds, applying a continuous down pressure of at least 50,000 pounds, equipped with a rock auger that contains conical carbide-tipped (“Kennemetal”) teeth.

D. Nominal Soil or Weathered Rock Seams:

Nominal soil or weathered rock seams below rock auger refusal will be excavated and considered as rock for rock excavation quantities. A nominal soil or weathered rock seam is one which is less than 2 feet thick. Where soil or weathered rock seams or voids of 2 feet or greater are excavated within a mixed rock/soil or rock/weathered rock profile, excavation is classified as soil/weathered rock excavation until rock auger refusal is again established.

1.6 MEASUREMENT AND PAYMENT FOR ROCK EXCAVATION

A. Measurement: Excavation type in units of length shall be considered to change at the upper contact with a different excavation type as defined by section 1.5.

B. Payment: Contract unit rates per length of each type of caisson shall be provided for each excavation condition type noted above in Section 1.5. Contract price and time will be adjusted for overruns or underruns in accordance with Articles, DIFFERING SITE CONDITIONS, CHANGES and CHANGES-SUPPLEMENT of the GENERAL CONDITIONS as applicable.

C. Payment for Differing Site Conditions: No payment will be made for any rock excavation beyond caisson limits unless additional excavation is directed by the COR. When rock excavation, as classified, is encountered, contract price and time will be adjusted in accordance with Articles, DIFFERING SITE CONDITIONS, CHANGES and CHANGES-SUPPLEMENT of the GENERAL

CONDITIONS as applicable.

1.7 TOLERANCES

Install caissons with not more than the lesser of 1/24th of caisson shaft diameter or 3 inches from design center location. Caissons shall not be out of plumb more than 1 inch in 10 feet for the full depth. Cross sections of shafts and bells shall not be less than design dimensions. Batter caissons shall be installed a maximum of 2 percent of length from specified inclination.

1.8 SUBMITTALS

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

SAMPLES.

31 63 26 - 3

B. Before beginning work, submit a detailed location plan and description of the proposed method of caisson installation, all of which shall be subject to the review and approval of the COR.

C. Shop Drawings shall comply with ACI 315 "Manual of Standard Practice for Detailing Reinforced

Concrete Structures". Furnish shop drawings prepared by a Professional Engineer licensed in the State of the project for the detailing, fabricating, bending, and placing of concrete reinforcement.

E. Reports:

1. Caisson record: Data as specified.

2. Rock excavation: Data as specified.

3. Soil Testing Agency Reports shall be issued showing material type and allowable bearing capacity at bottom of shaft within 24 hours observing each caisson.

4. Certified, "Caisson Field Record" for each caisson recording actual elevation of bottom, elevation of rock (if applicable), final centerline location of top, variation of shaft from plumb, bell dimension (if applicable), result of all tests and observations performed, material type and actual allowable bearing capacity of bottom, depth of socket into rock, levelness of bottom, seepage of water, still water level (if allowed to flood), elevation (top and bottom) of lining left in place, variation of shaft diameter (from those shown), and evidence of seams, voids or channels below bottom.

F. Certificates: Contractor’s qualifications as specified: Experienced specialty piling subcontractor having a minimum of 5 years successful experience installing Work of the same type required for this project. Employ only skilled tradesmen who are thoroughly experienced with the materials and equipment to be used in the Work.

G. Independent Testing and Inspection Agency: The Contractor shall retain an Independent Testing and Inspection Agency (Agency) to document, monitor, and production pile work. This Agency shall submit field reports and test results required for pile installations, and grout testing and inspection. They shall submit a pile installation report for each pile no later than three days after the installation is complete.

H. Qualification Data: For Installer, Land Surveyor, and Testing and Inspection Agency.

I. Upon completion of caisson installations, the Contractor shall submit five copies of drawings indicating actual in-place pile locations. The Contractor shall pay for all surveying costs.

Drawings must be submitted prior to beginning any pile cap or mat installation. One electronic copy of the drawings shall be submitted in AutoCAD DWG format on CD-ROM.

J. Record drawings at Project closeout according to Division 01 Section "Closeout Procedures."

1.9 QUALITY CONTROL

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

31 63 26 - 4

B. A Quality Control Program shall be submitted by the Contractor at least two weeks prior to the commencement of work. The implementation of a Contractor Quality Control Program does not relieve the Contractor from the responsibility to provide work in accordance with the Contract

Documents, applicable codes, regulations, and Governing Authorities.

C. Contractor's Independent Testing and Inspection Agency (Agency): The Contractor shall retain at his own expense, the services of a qualified Independent Testing and Inspection Agency, licensed in the state of the project, to provide testing and inspection services during the installation of all foundation piling involved in this Work. This firm shall also provide consultation services to the Contractor if problems are encountered during the execution of the Work. The

Agency shall be primarily concerned with the testing and construction methods which will result in finished foundation piling of the required quality and strength. The Agency shall also be concerned with preventing settlement and/or damage to surrounding structures, roads, utilities, embankments, etc., both within the property lines and on adjoining properties during the construction.

D. The Agency shall be experienced in the testing and installation of caisson foundations. It shall have been involved in at least 8 different caisson projects in the last 5 years, and shall have experience in recommending, testing, and specifying caissons for similar subsurface conditions.

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

F. Contractor's Grout Mix Designer: The Contractor shall employ, at his own expense, a testing laboratory to design grout mixes, conduct tests and submit reports for the design mixes. The

Grout Mix Designer shall be qualified according to ASTM C1077 and ASTM E329 to perform material evaluation tests and to design concrete mixes, as documented according to ASTM E548.

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

1.10 APPLICABLE PUBLICATIONS

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

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

A36/A36M-08 ............................. Standard Specification for Carbon Structural Steel

A283/A283M-03(2007) ............... Standard Specification for Low and Intermediate Tensile

Strength Carbon Steel Plates

A615/A615M-09b ....................... Standard Specification for Deformed and Plain Carbon Steel

Bars for Concrete Reinforcement

31 63 26 - 5

A929/A929M-01(2007) ............... Standard Specification for Steel Sheet, Metallic Coated by the

Hot Dip Process for Corrugated Steel Pipe

A996/A996M-09b ....................... Standard Specification for Rail Steel and Axle Steel Deformed and Bars for Concrete Reinforcement

C33-11a ..................................... Standard Specification for Concrete Aggregates

C94/C94M-12 ............................. Standard Specification for Ready Mixed Concrete

C150-C50M-11 ........................... Standard Specification for Portland Cement

C494/C494M-11 ......................... Standard Specification for Chemical Admixtures for Concrete

C618-12 ..................................... Standard Specification for Coal Fly Ash and Raw or Calcined

Natural Pozzolan for Use in Concrete

C989-C989M-11 ......................... Standard Specification for Slag Cement for Use in Concrete and

Mortars

C1017/C1017M-07 ..................... Standard Specification for Chemical Admixtures for Use in

Producing Flowing Concrete

C. American Concrete Institute (ACI):

211.1-91 (2009) .......................... Standard Practice for Selecting Proportions for Normal, Heavyweight and Mass Concrete

301-10 ........................................ Specifications for Structural Concrete

315-99 ........................................ Details and Detailing of Concrete Reinforcement

D. American Welding Society (AWS):

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

D1.4 (1998) ................................ Structural Welding Code – Reinforcing Steel

PART 2 - PRODUCTS

2.1 MATERIALS

A. Steel Reinforcement: ASTM A615/A615M, or 996, Grade 60, deformed.

B. Portland Cement: ASTM C150, Type I or II.

C. Fly Ash/Slag:

1. Fly Ash Admixture: ASTM C618, Class C or F.

2. Ground Granulated Blast-Furnace Slag: ASTM C989, Grade 100 or 120.

D. Normal-Weight Aggregate: ASTM C33, uniformly graded, 19 mm (3/4-inch) maximum aggregate size.

E. Water: Potable, complying with ASTM C94/C94M requirements.

31 63 26 - 6

F. Admixtures: Certified by manufacturer to contain not more than 0.1 percent water-soluble chloride ions by mass of cementitious material and to be compatible with other admixtures and cementitious materials. Do not use admixtures containing calcium chloride.

SPEC WRITER NOTE: If desired, select admixtures from subparagraphs below.

1. Water-Reducing Admixture: ASTM C494, Type A.

2. Water-Reducing and Retarding Admixture: ASTM C494, Type D.

3. High-Range, Water-Reducing Admixture: ASTM C494, Type G.

4. Plasticizing and Retarding Admixture: ASTM C1017, Type II.

G. Steel Casings: All casing shall meet ASTM A283, Grade C; or ASTM A36, carbon-steel plate, with joints full-penetration welded according to AWS D1.1, or ASTM A929/A929M, steel sheet, zinc coated corrugated steel. The Contractor shall design shells to withstand drilling forces and earth pressures and reinforce the bottom cutting edge as required for proper drilling and sealing of the shells into the rock. The cutting edge shall be capable of coring through at least 10 ft of broken or solid rock. A minimum of 2% out of roundness of the diameter shall be considered in the design of the shell. All seams shall be welded and watertight.

H. Concrete Mix: Prepare design mixes according to ACI 211.1 and ACI 301 for each type and strength of concrete determined by either laboratory trial mix or field test data bases. Use a qualified testing agency for preparing and reporting proposed mix designs for laboratory trial mix basis. Proportion mixes according to ACI 211.1 and ACI 301 to provide normal-weight concrete with the following properties:

1. Compressive Strength (28 Days): 5000 psi.

2. Minimum Slump: Capable of maintaining a slump of 5 inches plus or minus 1 inch.

3. Do not air entrain concrete for caissons

4. Limit water-soluble, chloride-ion content in hardened concrete to 0.15 percent by weight of cement.

5. Concrete-mix design adjustments may be considered if characteristics of materials, project conditions, weather, test results, or other circumstances warrant. Resubmission and approval of proposed changes to concrete-mix proportions are the responsibility of the

Contractor.

I. Concrete Mixing: Measure, batch, mix, and deliver concrete according to ASTM C 94, and furnish batch ticket information. Do not add water to concrete mix after mixing unless a procedure per

ACI 301 is submitted to and approved by the COR. Maintain concrete temperature less than

90 degree Fahrenheit.

31 63 26 - 7

PART 3 - EXECUTION

3.1 GENERAL

A. Size: Minimum sizes and types of caissons are shown. Proposal to use caissons of sizes and types different from those shown may be accepted if submitted in writing to COR for approval and provided the following conditions are met:

1. Least dimension of caisson is equal to or greater than least dimension shown.

2. Enlargement at base of caisson is in bell-form with dimensions equal to or greater than minimum shown.

3. If volume of caisson as constructed is greater than that shown, bearing area at base is increased so that additional weight is distributed to bearing material at no more than 3ksf).

4. Entire caisson receives full lateral support from surrounding material.

B. Changes: Requests for change in size or type of caisson from those shown shall be accompanied by calculations and other documentation necessary to show that proposed changes will meet load requirements. Do not proceed with changes before receiving written approval from COR.

C. Temporary Steel Casings: Install casings for protection of workers and inspection personnel, for prevention of cave-ins or displacement of earth walls, and for retention of ground water.

D. Defective Casings: Do not install buckled, distorted or otherwise damaged casings. Replace casings damaged or disturbed during construction, casings that are not mud-tight or otherwise not in accordance with drawings or specifications, at no additional cost to the Government.

E. Survey: Registered Professional Land Surveyor or Registered Civil Engineer, specified in Section

01 00 00, GENERAL REQUIREMENTS, shall establish lines and levels and stake caisson locations.

3.2 EXCAVATION

A. Excavation and construction methods shall result in minimum disturbance of surrounding material and full lateral support of caissons by surrounding material.

B. Remove boulders and rock in caissons such as rock seams underlain with soil seams, sloping rock or rock otherwise unsatisfactory for bearing.

C. If materials with satisfactory bearing strength occur at elevations higher or lower than those shown, place bottom of caissons at higher or lower elevations, subject to approval of COR.

D. Excavate caissons to dimensions and required bearing strata or elevations shown on contract drawings. Maintain sidewall stability during drilling. Excavate holes for closely spaced caissons, and those occurring in fragile strata, only after adjacent holes are filled with concrete and allowed to set. The excavation shall be accomplished by hand or machine excavation as required.

Caisson drilling equipment shall have the minimum torque capacity and downward force capacity for the contract site conditions. Bottoms of caissons shall be cleaned of loose or soft materials

31 63 26 - 8 and leveled. If bottoms are sloping rock, excavate to a level plane or step with maximum step height less than 1/4 the width or diameter of the bearing area. All material removed from the caisson holes shall be removed from the ground around the casing before concrete placement is started and shall be disposed of by the Contractor off site in areas submitted to and approved by the Engineer.

E. Excavations for utilities, support of excavations, or other purposes shall be kept a minimum distance of two shaft diameters away from the outer edge of the caisson.

3.3 PLACING CONCRETE

A. Before placing concrete, the tip of the caisson shall be observed and approved by a qualified testing agency registered and licensed in the state. The testing agency shall be retained by the

Contractor and approved by the COR. The shaft shall be inspected, cleared of mud, water, loose material, and debris.

B. Place concrete using a down pipe to direct flow of concrete. Except in presence of water, concrete may fall freely up to a maximum height of 9.14 meters (30 feet) provided the concrete does not hit the sides of the caisson. Use tremie pipe or pump if distance is greater than 9.14 meters (30 feet).

C. Withdraw casings, as concrete is deposited, maintaining top surface of concrete constantly at least 1800 mm (6 feet) above lower end of casings. Place concrete to form a monolithic cylindrical shaft having full lateral support from surrounding undisturbed materials. Strike finished top surface of concrete to true plane at required elevation.

D. Concrete placement in each caisson shall be one continuous operation. If placing operation must be stopped, leave surface approximately level. If concrete has hardened, clean surface and slush with a 1 to 1 cement-sand grout before placing operation is resumed. Concrete pours shall not begin within one hour of darkness. If this type of continuous sequential operation cannot be performed, the Contractor shall submit for approval by the COR a method of securing the open excavation. The Contractor shall not leave excavations open overnight without receiving prior written approval from the COR.

E. When water is present, control water level to within 2 inches of bottom of the caisson by pumping.

If impossible or impractical to control water, secure written permission from COR to place concrete through water by means of a watertight tremie.

1. When placing concrete under water, discharge end of tremie shall be submerged in fresh concrete and shaft of tremie maintained full of concrete to point above water level.

2. Increase cement content of concrete required to be placed in water by one sack per cubic yard of concrete.

31 63 26 - 9

3.4 CAISSON RECORD

A. For each caisson placed and before superstructure framing is placed, submit to COR for approval a certified report recording following information prepared by Registered Professional Land

Surveyor or Registered Civil Engineer.

B. Caisson number, length, and bearing material.

C. Location.

D. Concrete and steel reinforcement properties.

E. Plumbness.

F. Dates:

1. Excavation completed.

2. Concrete placed.

G. Diameters:

1. Top of shaft.

2. Bottom of shaft.

3. Bell.

H. Elevations:

1. Top of ground.

2. Top of concrete.

3. Top of rock.

4. Bottom of caisson.

3.5 CLEAN UP:

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

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

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