Bid Notice-Grading_ Drainage_ Paving_ Signals _ Structures - Bucombe County.pdf

STATE OF NORTH CAROLINA

DEPARTMENT OF TRANSPORTATION

JOSH STEIN DANIEL H. JOHNSON

GOVERNOR SECRETARY

Mailing Address:

NC DEPARTMENT OF TRANSPORTATION

CONTRACT STANDARDS AND DEVELOPMENT

1591 MAIL SERVICE CENTER

RALEIGH, NC 27699-1591

Telephone: (919) 707-6900

Fax: (919) 250-4127

Customer Service: 1-877-368-4968

Website: www.ncdot.gov

Location:

1020 BIRCH RIDGE DR.

RALEIGH, NC 27610

October 8, 2026

Addendum No. 1

RE: Contract # C205222

WBS # 34165.3.8

STATE FUNDED

Buncombe County (I-2513AC)

I-26/I-240 FROM NORTH OF I-40 TO SR-3548 (HAYWOOD RD)

November 17, 2026 Letting

To Whom It May Concern:

Reference is made to the plans and proposal furnished to you on this project.

The following revisions have been made to the proposal.

Page No. Revision

Proposal Cover Note added that reads

“Includes Addendum No. 1 Dated 10-8-2026”.

GT-11.1 thru 11.18 The UNIT PROJECT SPECIAL PROVISION entitled

DRILLED PIERS has been revised.

Please void the above listed existing pages in your proposal and staple the revised pages thereto.

Sincerely, Jon Weathersbee, PE

State Contract Officer

JHW/jcm

Attachments cc: Mr. Troy B. Brooks, PE Mr. Forrest Dungan, PE

Mr. Tim Anderson, PE Ms. Jaci Kincaid http://www.ncdot.gov/

C205222 (I-2513AC) Buncombe County

Mr. Ken Kennedy, PE Mr. Josh Sellers, PE

Mr. Malcolm Bell Project File (2)

PROPOSAL

STATE OF NORTH CAROLINA

DEPARTMENT OF TRANSPORTATION

RALEIGH, N.C.

WBS

T.I.P NO.

COUNTY

CONTRACT ID

ROUTE NO.

LOCATION

TYPE OF WORK

NOTICE:

ALL BIDDERS SHALL COMPLY WITH ALL APPLICABLE LAWS REGULATING THE PRACTICE OF GENERAL CONTRACTING AS CONTAINED IN CHAPTER 87 OF THE

GENERAL STATUTES OF NORTH CAROLINA WHICH REQUIRES THE BIDDER TO BE LICENSED BY THE N.C. LICENSING BOARD FOR CONTRACTORS WHEN BIDDING

ON ANY NON-FEDERAL AID PROJECT WHERE THE BID IS $40,000 OR MORE, EXCEPT FOR CERTAIN SPECIALTY WORK AS DETERMINED BY THE LICENSING BOARD.

BIDDERS SHALL ALSO COMPLY WITH ALL OTHER APPLICABLE LAWS REGULATING THE PRACTICES OF ELECTRICAL, PLUMBING, HEATING AND AIR CONDITIONING

AND REFRIGERATION CONTRACTING AS CONTAINED IN CHAPTER 87 OF THE GENERAL STATUTES OF NORTH CAROLINA. NOTWITHSTANDING THESE LIMITATIONS

ON BIDDING, THE BIDDER WHO IS AWARDED ANY FEDERAL - AID FUNDED PROJECT SHALL COMPLY WITH CHAPTER 87 OF THE GENERAL STATUTES OF NORTH

CAROLINA FOR LICENSING REQUIREMENTS WITHIN 60 CALENDAR DAYS OF BID OPENING.

BIDS WILL BE RECEIVED AS SHOWN BELOW:

34165.3.8

I-2513AC

BUNCOMBE

C205222

I-26/240

MILES 1.742

I-26/I-240 FROM NORTH OF I-40 TO SR-3548 (HAYWOOD RD).

GRADING, DRAINAGE, PAVING, SIGNALS, AND STRUCTURES.

THIS IS A ROADWAY & STRUCTURE PROPOSAL

DATE AND TIME OF BID OPENING:

FEDERAL-AID NO. STATE FUNDED

5% BID BOND OR BID DEPOSIT REQUIRED

Nov 17, 2026 AT 02:00 PM

INCLUDES ADDENDUM No.1 DATED 10-8-2026

I-2513AC GT-#11.1 BUNCOMBE COUNTY

DRILLED PIERS:

(11-17-26)

Revise the Standard Specifications as follows:

Replace Section 411 with the following:

SECTION 411

DRILLED PIERS

411-1 DESCRIPTION

Construct drilled piers consisting of CIP reinforced concrete cylindrical sections in excavated holes typically stabilized with casings or slurry. Provide permanent casings, standard penetration tests, integrity testing and assistance with the shaft inspection device as noted in the plans.

Construct drilled piers with the required resistances and dimensions in accordance with the contract and accepted submittals. Use a prequalified Drilled Pier Contractor to construct drilled piers.

Define “excavation” and “hole” as a drilled pier excavation and “pier” as a drilled pier. Define

“permanent casing” as a casing that remains in the excavation and acts as a form for Drilled Pier concrete and “temporary casing” as any casing that is not permanent. Define “rock” as a continuous intact natural material with a standard penetration resistance of 0.1 foot or less per 60 blows or a rock auger penetration rate of less than 2 inches per 5 minutes of drilling at full crowd force or as determined by the Engineer when rock is not encountered as expected based on these criteria. This definition excludes discontinuous loose natural materials such as boulders and man-made materials such as concrete, steel, timber, etc. and is not for measurement and payment purposes. See Article 411-7 for measurement and payment of drilled piers.

411-2 MATERIALS

Refer to Division 10.

Item Section

Grout, Type 2 1003

Portland Cement Concrete, Class Drilled Pier 1000

Reinforcing Steel 1070

Provide Type 3 material certifications in accordance with Article 106-3 for permanent casings and roller, chair, steel pipe and cap materials. Store steel materials on blocking at least 12 inches above the ground and protect it at all times from damage; and when placing in the work make sure it is free from dirt, dust, loose mill scale, loose rust, paint, oil or other foreign materials.

Load, transport, unload and store drilled pier materials so materials are kept clean and free of damage.

(A) Steel Casing

Define “casing” as a temporary or permanent casing. If permanent casing is required for an excavation, the largest diameter casing in the hole is the permanent casing. This does not apply to working casings around permanent casings as approved by the Engineer.

I-2513AC GT-#11.2 BUNCOMBE COUNTY

Use smooth non-corrugated clean watertight steel casings of ample strength to withstand handling and installation stresses and pressures imposed by concrete, earth, backfill and fluids.

(1) Temporary Casings

Provide temporary casings with a nominal wall thickness of at least 0.375 inch and an outside diameter equal to or larger than the design pier diameter for which temporary casing is used.

(2) Permanent Casings

Use permanent casings with a yield strength of at least 36 ksi and a nominal wall thickness that meets Table 411-1.

TABLE 411-1

MINIMUM PERMANENT CASING WALL THICKNESS

Casing Diameter Nominal Wall Thickness

< 48" 0.375"

48" - 78" 0.500"

> 78" 0.625"

Provide permanent casings with an outside diameter equal to the design pier diameter for which permanent casing is used unless larger diameter permanent casings are approved by the Engineer.

(B) Slurry

Define “slurry” as bentonite or polymer slurry. Mix bentonite clay or synthetic polymer with water to make bentonite or polymer slurry.

(1) Bentonite Slurry

Provide bentonite slurry that meets Table 411-2.

TABLE 411-2

BENTONITE SLURRY REQUIREMENTSA

Property ANSI/API RPB 13B-1 Requirement

DensityC

(Mud Weight)

Section 4

Mud Balance

64.3 - 72.0 pcf

Viscosity Section 6.2

Marsh Funnel 28 - 50 sec/qt

Sand Content Section 9 ≤ 4 %D

≤ 2 %E pH Section 11

Glass Electrode pH MeterF 8 - 11

A. Slurry temperature of at least 40°F required

B. American National Standards Institute/American Petroleum Institute Recommended

Practice

C. Increase density requirements by 2 pcf in saltwater

D. In tanks before pumping slurry into excavations

I-2513AC GT-#11.3 BUNCOMBE COUNTY

E. In excavations immediately before placing concrete

F. pH paper is also acceptable for measuring pH

(2) Polymer Slurry

Use polymer slurry products qualified by the Department. Provide polymer slurry with density, viscosity, sand content and pH properties that meet the product requirements. The polymer slurry QPL with the property requirements for each qualified polymer slurry product is available on the Geotechnical Engineering

Unit’s website.

(C) Rollers and Chairs

Use rollers and chairs that are non-metallic and resistant to corrosion and degradation.

Provide rollers with the necessary dimensions to maintain the minimum required concrete cover shown in the plans and center rebar cages within excavations. Use chairs of sufficient strength to support rebar cages in excavations and of the size necessary to raise cages off bottom of holes to maintain the minimum required distance shown in the plans.

(D) Steel Pipes and Caps

Use Schedule 40 black steel pipes for access tubes for crosshole sonic logging (CSL).

Provide CSL tubes with an inside diameter of at least 1.5 inches. Use CSL tubes with a round, regular inside diameter free of defects and obstructions, including any pipe joints, in order to permit free, unobstructed passage of probes for CSL testing. Provide watertight CSL tubes free of corrosion with clean internal and external faces to ensure a good bond between concrete and tubes. Fit CSL tubes with watertight plastic caps on the bottom and removable caps on top.

(E) Drilled Pier Concrete

Use drilled pier concrete material meeting the requirements of Section 1000, except as modified below:

(1) Supplementary Cementitious Materials (SCMs)

Add SCMs to reduce peak concrete hydration temperature, improve thermal performance, and mitigate risk of thermal cracking in Drilled Pier Concrete in accordance with Table 411-3. Use any one or combination of the SCMs that satisfies the required minimum dosages below:

(a) ≥ 25% Class F fly ash that meets ASTM C618

(b) ≥ 35% Class C fly ash that meets ASTM C618

(c) ≥ 35% slag cement that meets ASTM C989/C989M

(d) ≥ 5% silica fume that meets ASTM C1240 with ≥ 25% slag cement

(e) ≥ 5% silica fume that meets ASTM C1240 with ≥ 20% Class F fly ash that meets ASTM C618

Use SCMs found on the Department’s approved producer/supplier list. Concrete mixtures containing high alkali cements must also utilize the appropriate SCMs and minimum substitution rates provided in Article 1024-1.

I-2513AC GT-#11.4 BUNCOMBE COUNTY

(2) Equivalent Cement Content (ECC)

Determine the ECC on a per cubic yard basis with the following formula:

ECC= 1.0(PC) + 0.5(FAF) + 0.8(FAC) + 1.2(SF) + 1.0(SC)

Where:

PC = Portland cement

FAF = Class F fly ash

FAC = Class C fly ash

SF = Silica fume

SC = Slag cement

All units are in pounds per cubic yard.

ECC shall meet the requirements of Table 411-3 unless otherwise supported by a temperature prediction model in accordance with Subarticle 411-2(E)(3)(b).

(3) Thermal Control

(a) Use appropriate thermal control measures to reduce the peak concrete hydration temperature in Drilled Pier Concrete. Methods for controlling concrete temperature may include, but are not limited to, the following:

(i) Selecting constituent materials that minimize the heat generated by concrete hydration.

(ii) Cooling constituent materials to reduce the temperature of concrete in its plastic state.

(iii) Controlling the rate of concrete placement.

(iv) Other methods proposed by the Contractor and approved by the Engineer.

At a minimum, provide thermal control for Drilled Pier Concrete in accordance with Table 411-3.

TABLE 411-3

THERMAL CONTROL REQUIREMENTS FOR DRILLED PIER CONCRETE

D

Drilled

Pier

DiameterA

(ft)

SCMs

Required?

(Yes/No)

Max

ECC

(lb/cy)

Max Temp with

SCMsC (°F)

Max

Temp without

SCMs

(°F)

Temp

Prediction

Required?

(Yes/No)

Temp

Monitoring

Required?

(Yes/No)

D < 5 No N/A 158 No No

5 ≤ D < 6 Yes 625 185 N/A No Yes

D ≥ 6 Yes B N/A Yes Yes

A. Drilled pier diameter is the largest constructed diameter for any portion of a pier.

B. As determined by temperature prediction model

C. For a list of SCM’s allowed see Subarticle 411-2(E)(1)

I-2513AC GT-#11.5 BUNCOMBE COUNTY

(b) Temperature Prediction

Use the Schmidt Method or numerical thermal modeling as described in

Concrete: Microstructure, Properties, and Materials by Mehta and Monteiro

(2014) or other method approved by the Engineer to predict concrete hydration temperature. Temperature predictions are required for each Drilled

Pier Concrete mix design with a different drilled pier condition. Variations in constructed drilled pier diameter or drilled piers with permanent steel casing are considered different drilled pier conditions. Submit temperature prediction results and any planned thermal control measures at least 30 days before beginning Drilled Pier Concrete placement.

(c) Temperature Monitoring

Monitor concrete hydration temperature for the first drilled pier constructed with each Drilled Pier Concrete mix with a different drilled pier condition as described in Subarticle 411-2(E)(3)(b). Measure temperature at the center of the drilled pier diameter using two redundant thermal sensors inserted at least

1.5 × pier diameters below the top of pier and in accordance with ASTM

D7949, Method B. Begin recording temperature data to the nearest one-degree Fahrenheit immediately after completing concrete placement. Record temperatures using an hour or smaller interval of time. Continue recording temperatures until at least 24 hours after the peak temperature has passed. If a temperature limit is exceeded, continue monitoring until all temperature values fall below the specified limit, even if the 24-hour requirement has been met. Submit temperature monitoring data within 24 hours after completing monitoring and before placing another drilled pier under the same conditions.

If temperature limits are exceeded during monitoring, submit a revised thermal control plan including but not limited to revised concrete mix designs, lower concrete placement temperature, or other modifications proposed by the contractor for review by the Engineer. Do not place additional drilled piers under the same conditions until the revised thermal control plan has been reviewed by the Engineer. Drilled piers that exceed the temperature limits established in Table 411-3 are considered unacceptable unless the Contractor demonstrates through an engineering analysis that the drilled pier is acceptable to the Engineer.

(d) Concrete Placement Temperature

For drilled piers with constructed diameters of 5 feet or greater, maintain concrete temperature at time of placement between 40°F and 75°F. Placement temperatures up to 85°F may be permitted when supported by temperature prediction or monitoring as specified in Subarticle 411-2(E)(3)(b) and (c).

When placement temperatures above 75°F are permitted based on temperature monitoring, continue monitoring subsequent drilled piers until monitoring demonstrates that the maximum temperature specified in Table 411-3 will not be exceeded at the higher placement temperature.

I-2513AC GT-#11.6 BUNCOMBE COUNTY

(4) Concrete Slump Loss

Place concrete within the slump requirements listed in Table 1000-1 and maintain a minimum slump of 5 inches throughout the elapsed time. The elapsed time for placing drilled shaft concrete includes the concrete mixing and transit time, the concrete placement time, and the time required to remove any tremies, temporary casings, etc. Include the estimated elapsed time for concrete placement in the drilled shaft installation plan.

For drilled piers with a theoretical concrete volume of 75 cubic yards or more and an estimated elapsed time greater than 2 hours, perform a field slump loss test.

Perform the slump loss test in accordance with the procedure posted on the

NCDOT Materials and Tests Unit website and demonstrate to the Engineer, before drilled pier concrete placement, that the concrete will maintain a slump of

5 inches or greater for the estimated elapsed time. Place concrete if it’s temperature at the time of placement into the drilled pier is no more than 10°F higher than the slump loss test temperature. Use ice or other concrete-cooling ingredients to lower concrete temperature or run additional slump loss tests at the higher temperatures.

411-3 PRECONSTRUCTION REQUIREMENTS

(A) Drilled Pier Construction Plan

Submit the proposed drilled pier construction plan for all drilled piers for acceptance by the Engineer. Provide an electronic copy of this plan at least 30 days before starting drilled pier construction. Do not begin drilled pier construction until a construction plan is accepted by the Engineer. Provide detailed project specific information in the drilled pier construction plan that includes the following:

(1) Overall description and sequence of drilled pier construction;

(2) List and sizes of equipment including cranes, drill rigs, vibratory and downhole hammers, Kelly bars, augers, core barrels, casings (diameters, thicknesses and lengths), cleanout buckets, air lifts, pumps, slurry equipment, tremies, pump pipes and other equipment;

(3) Procedures for casing installation and temporary casing removal including how telescoping temporary casings will be removed;

(4) If applicable, details of slurry testing and use including intended purpose, product information and additives, manufacturer’s recommendations for use, name and contact information for slurry manufacturer’s technical representative, mixing and handling procedures and how slurry level will be maintained above the highest piezometric head;

(5) Methods for drilling and cleaning holes including how cores will be removed and drilling spoils and slurry will be handled and disposed of;

I-2513AC GT-#11.7 BUNCOMBE COUNTY

(6) Details of CSL tubes, caps and joints including pipe size and how tubes will be attached to reinforcing steel;

(7) Procedures for lifting and setting reinforcing steel including how rebar cages will be supported and centralized;

(8) Procedures for placing concrete including how tremies and pump pipes will be controlled and contaminated concrete will be contained;

(9) Concrete mix design that meets Section 1000;

(10) Approved packaged grout or grout mix design that meets Section 1003;

(11) CSL Consultant including Field and Project Engineer; and

(12) Other information shown in the plans or requested by the Engineer.

If alternate construction procedures are proposed or necessary, a revised drilled pier construction plan submittal may be required. If the work deviates from the accepted submittal without prior approval, the Engineer may suspend drilled pier construction until a revised plan is accepted by the Engineer.

(B) Preconstruction Meeting

Before starting drilled pier construction, hold a drilled pier preconstruction meeting to discuss the installation, monitoring and inspection of the drilled piers. Schedule this drilled pier preconstruction meeting with the Engineer after the Drilled Pier Contractor mobilizes to the site. If this meeting occurs before all drilled pier submittals have been accepted by the Engineer, additional drilled pier preconstruction meetings may be required before beginning construction of drilled piers without accepted submittals. The

Prime Contractor and Drilled Pier Contractor Superintendent shall attend the drilled pier preconstruction meetings.

411-4 CONSTRUCTION METHODS

Do not excavate holes, install piles or allow equipment loads or vibrations within 20 feet of completed piers until 16 hours after drilled pier concrete reaches initial set.

When drilling from a barge, use a fixed template that maintains hole position and alignment during drilled pier construction. Do not use floating templates or templates attached to barges.

Check for correct drilled pier alignment and location before beginning drilling. Check plumbness of Kelly bars before beginning and frequently during drilling.

For drilled piers constructed with slurry or permanent casings, the pier diameter may be 2 inches less than the design pier diameter shown in the plans. For all other drilled piers, construct piers with the minimum required diameters shown in the plans except for portions of drilled piers in rock which may be 2 inches less than the design pier diameter.

Install drilled piers with tip elevations no higher than shown in the plans or approved by the

Engineer. Provide piers with the minimum required tip resistance and, when noted in the plans, penetration into rock.

(A) Excavation

I-2513AC GT-#11.8 BUNCOMBE COUNTY

Excavate holes with equipment of the sizes required to construct drilled piers. Use equipment and methods accepted in the drilled pier construction plan or approved by the

Engineer. Inform the Engineer of any deviations from the accepted plan.

Use drill rigs with sufficient capacity to drill through soil, rock, boulders, timbers, man-made objects and any other materials encountered and drill 20 feet deeper or 20% longer than the maximum drilled pier length shown in the plans, whichever is greater. Drilling below pier tip elevations shown in the plans may be required to attain sufficient resistance.

Do not use blasting to advance drilled pier excavations. Blasting for core removal is only permitted when approved by the Engineer. See Articles 107-11 and 107-12 for protection of public and private property and control of siltation, dust and air and water pollution from blasting, drilling and excavating with down-the-hole hammers. Contain and dispose of drilling spoils and waste concrete in accordance with Section 802 or as directed by the

Engineer. Drilling spoils consist of all materials and fluids removed from excavations.

Stabilize excavations with only casings or slurry and casings except, as approved by the

Engineer, portions of excavations in rock. Use casings or slurry in rock if unstable material is anticipated or encountered. Stabilize excavations from beginning of drilling through concrete placement. If excavations become unstable, the Engineer may suspend drilling and require a revised drilled pier construction plan. If it becomes necessary to replace a casing during drilling, backfill the excavation, insert a larger casing around the casing to be replaced or stabilize the excavation with slurry before removing the casing.

When noted in the plans, do not dewater drilled pier excavations. Otherwise, if excavations are in rock, dewater excavations to the satisfaction of the Engineer.

(B) Casings

Provide temporary casings to stabilize holes and protect personnel entering excavations.

Permanent casings may be required as noted in the plans. Install permanent casings with tip elevations no deeper than shown in the plans or approved by the Engineer. Additional drilled pier length and reinforcing steel may be required if permanent casings are installed below elevations noted in the plans.

Install casings in continuous sections. Overlap telescoping casings at least 24 inches.

Remove portions of permanent casings above the ground line or top of piers, whichever is higher, after placing concrete. Do not cut off permanent casings until Drilled Pier concrete attains a compressive strength of at least 3,000 psi.

When using slurry construction without permanent casings, temporary casings at least 10 feet long are required at top of excavations. Maintain top of casings at least 12 inches above the ground line.

(C) Slurry Construction

Unless noted otherwise in the plans, slurry construction or polymer slurry is at the

Contractor’s option.

Use slurry and additives to stabilize holes in accordance with the manufacturer’s recommendations. Provide a technical representative employed by the slurry

I-2513AC GT-#11.9 BUNCOMBE COUNTY

manufacturer to assist and guide the Drilled Pier Contractor onsite during the construction of the first drilled pier. If problems are encountered during drilled pier construction, the Engineer may require the technical representative to return to the site.

Provide documentation that mixing water is suitable for slurry. Use slurry equipment that is sufficient for mixing, agitating, circulating and storing slurry. Thoroughly premix slurry with water in tanks before pumping into excavations. Allow bentonite slurry to hydrate at least 24 hours in tanks before use.

Pump slurry into excavations before encountering water. Maintain slurry level at least 5 feet or one pier diameter, whichever is greater, above the highest piezometric head along the drilled pier length. The highest piezometric head is anticipated to be the static water or groundwater elevation. However, the Drilled Pier Contractor is responsible for determining the highest piezometric head for each pier.

Maintain the required slurry properties at all times. Desand or replace slurry as needed to meet the required sand content in tanks before pumping slurry into excavations and in excavations immediately before placing concrete.

(1) Time

Agitate bentonite slurry in holes at least every 4 hours. If this 4-hour time limit is exceeded, the Engineer may require holes to be overreamed at least 1 inch and no more than 3 inches below casings. Overream holes with grooving tools, overreaming buckets or other approved methods.

Construct drilled piers so the maximum time slurry is in contact with uncased portions of holes from drilling through concrete placement does not exceed 36 hours. If this 36 hour time limit is exceeded, the Engineer may require the hole diameter to be enlarged at least 6 inches. If the enlarged hole diameter is greater than the permanent casing diameter, replace casing with a larger permanent casing with an outside diameter equal to the diameter of the enlarged hole.

(2) Slurry Testing

Define a “sample set” as slurry samples collected from mid-height and within 2 feet of the bottom of slurry tanks or holes. Take a sample set from slurry tanks to test slurry before beginning drilling. Do not pump slurry into excavations until both slurry samples from tanks meet the required slurry properties. Take sample sets from excavations to test slurry at least every 4 hours and immediately before placing concrete. Do not place Drilled Pier concrete until both slurry samples from an excavation meet the required slurry properties. If any slurry test results do not meet the requirements, the Engineer may suspend drilling until both samples from a sample set meet the required slurry properties.

Sign, date and submit slurry test reports upon completion of each pier. The

Department reserves the right to perform comparison slurry tests at any time.

(3) Disposal

Comply with all Federal, State and local regulations, as well as the project permits and commitments, when disposing of slurry and drilling spoils mixed with slurry.

I-2513AC GT-#11.10 BUNCOMBE COUNTY

Contain slurry and drilling spoils and keep out of water at all times.

(D) Cleaning and Inspection

Provide clean holes with level bottoms so elevations within bottom of holes do not vary by more than 12 inches. Remove soft and loose material from bottom of holes using methods accepted in the drilled pier construction plan or approved by the Engineer.

When bottom of holes are not hand cleaned, remove sediment from holes with cleanout buckets, air lifts or pumps.

After cleaning is complete, provide all equipment, personnel and assistance required for the Engineer to visually inspect holes from above or by entering excavations. Remove all cleaning and drilling equipment from holes during inspections and do not interfere with inspections.

(1) Tip Resistance

If the Engineer determines that the material below an excavation does not provide the minimum required tip resistance, increase the drilled pier length and lengthen reinforcing steel as directed by the Engineer. One of the following methods may be required to check the conditions and continuity of material below excavations.

(a) Test Hole

If excavations are in rock, drill a 1.5 inch diameter test hole at least 6 feet below bottom of holes to determine the continuity of rock below holes.

(b) Standard Penetration Test

Standard penetration tests (SPT) may be required as noted in the plans.

When required, drive a split-barrel sampler 18 inches below bottom of holes or to refusal in accordance with ASTM D1586. Perform SPT in holes at least 12 inches away from casing walls and support drill rods so rods remain vertical and straight. Report the number of blows applied in each 6 inch increment and provide recovered samples to the Engineer.

The Engineer will determine the standard penetration resistance required.

(2) Bottom Cleanliness

Holes are clean if at least 50% of bottom of holes has less than 0.5 inch of sediment and no portions of bottom of holes have more than 1.5 inches of sediment. If bottom of holes does not meet this cleanliness criteria, remove sediment from holes until the Engineer determines holes are clean. One or more of the following methods may be required to inspect the bottom cleanliness of holes.

(a) Steel Probe

If drilled pier excavations are not dewatered or as directed by the

Engineer, provide a #10 rebar steel probe that is 24 inches long with a flat tip on one end and a non-stretch cable connected to the other end. Provide a cable long enough to lower the steel probe to the bottom of holes for the

Engineer to determine the amount of sediment in holes.

I-2513AC GT-#11.11 BUNCOMBE COUNTY

(b) Shaft Inspection Device

The Engineer may use the shaft inspection device (SID) as noted in the plans. The Engineer provides the SID and personnel to operate it. Notify the Engineer at least 2 days before finishing holes that will be inspected with the SID.

Assist the Engineer in handling the SID and associated equipment and supporting the SID during inspections. Provide working areas large enough for the SID, associated equipment and SID personnel within reach of the SID cables and clear view of holes being inspected. If necessary, provide a secure location to store the SID and associated equipment onsite overnight.

Approximately one hour is required to inspect a hole with the SID after the SID and associated equipment are set up. The Engineer will use the

SID to measure the amount of sediment at 5 locations around the bottom of holes.

(E) Reinforcing Steel and Concrete

Assemble rebar cages consisting of bar and spiral reinforcing steel shown in the plans.

Securely cross tie reinforcing steel at each intersection with double wire. Attach a chair under each reinforcing bar and rollers near the top and bottom of rebar cages and every

10 feet along cages in between. The number of rollers required at each location along rebar cages is one roller per foot of design pier diameter with at least 4 rollers per location. Space rollers equally around rebar cages at each location. Attach rollers so rollers are supported across 2 adjacent reinforcing bars and will freely rotate when rebar cages are lowered into excavations.

If CSL tubes are required, securely attach CSL tubes to spiral reinforcing steel on the inside of rebar cages with at least 3 inches of clearance to vertical reinforcing bars.

Extend CSL tubes from 6 inches above pier tip elevations to at least 2 feet above the ground line or top of permanent casings, whichever is greater. The number of CSL tubes required for each drilled pier is one tube per foot of design pier diameter with at least 4 tubes per pier. Space CSL tubes equally around rebar cages so distances between tubes measured around spiral reinforcing steel are uniform. Install CSL tubes as straight and parallel to each other as possible. Fit caps on top and bottom of CSL tubes.

After the Engineer determines that the material below excavations provides the minimum required tip resistance and holes are clean, place rebar cages and then concrete in excavations. Do not rack or distort rebar cages and CSL tubes when lifting and handling cages. Set rebar cages directly on bottom of holes or, as approved by the Engineer, hang cages from permanent casings. When hanging rebar cages, leave devices supporting cages in place until Drilled Pier concrete attains a compressive strength of at least 3,000 psi.

Do not delay placing cages or concrete unless excavations are cased to rock or otherwise approved. If delays occur, the Engineer may require removal of rebar cages to reinspect bottom cleanliness of holes. If bottom of holes does not meet the cleanliness criteria in

I-2513AC GT-#11.12 BUNCOMBE COUNTY

Subarticle 411-4(D)(2), remove sediment from holes until the Engineer determines holes are clean before resetting rebar cages.

After placing rebar cages with CSL tubes, remove top caps, fill tubes with clean water and reinstall caps before placing concrete. Check for correct cage position before placing concrete and keep rebar cages plumb during concrete placement. Maintain cage position so rebar cages do not move vertically more than 6 inches and columns or footings have the minimum required concrete cover shown in the plans.

Remove all temporary casings during concrete placement. Do not twist, move or otherwise disturb temporary casings until the concrete depth inside casings is at least 10 feet or half the head, whichever is greater, above the bottom of casing being disturbed.

Define “head” as the difference between the highest piezometric head along the drilled pier length and the static water elevation inside the excavation.

When removing temporary casings, maintain the required concrete depth above the bottom of casing being removed except when the concrete level is at or above top of piers. Sustain sufficient concrete depths to overcome pressures imposed by earth, backfill and fluids. As temporary casings are withdrawn, ensure fluids trapped behind casings is displaced upward and discharged out of excavations without contaminating or displacing concrete.

Pour concrete in excavations to form uniform jointless monolithic drilled piers. Do not trap soil, air, fluids or other contaminants in concrete. Remove contaminated concrete from top of piers at time of concrete placement.

Inform the Engineer of the volume of concrete placed for each pier. For piers constructed with slurry or as directed by the Engineer, record a graphical plot of depth versus theoretical and actual concrete volumes.

Dry or wet placement of concrete is at the Contractor’s option for piers constructed with only casings if the water inflow rate into excavations is less than 6 inches per half hour after removing any pumps from holes. Wet placement of concrete is required for all other drilled pier construction.

(1) Dry Placement

If holes are filling with water for dry placement of concrete, dewater excavations as much as possible before placing concrete. For drilled piers less than 80 feet long, pour concrete down the center of excavations so concrete does not hit reinforcing steel or excavation sidewalls. For piers longer than 80 feet, place concrete with a tremie or pump pipe down the center of excavations so length of free fall is less than 80 feet.

(2) Wet Placement

For wet placement of concrete, maintain static water or slurry levels in holes before placing concrete. Place concrete through steel tremies or pump pipes. Use tremies with watertight joints and a diameter of at least 10 inches. Pump concrete in accordance with Article 420-5. Use approved devices to prevent contaminating concrete when tremies or pump pipes are initially placed in excavations. Keep

I-2513AC GT-#11.13 BUNCOMBE COUNTY

tremies or pump pipes embedded into concrete at least 5 feet at all times except when the concrete is initially placed.

When the concrete level reaches the static water elevation inside the excavation, dry placement of concrete is permitted. Before changing to dry placement, pump water or slurry out of holes and remove contaminated concrete from the exposed concrete surface.

411-5 INTEGRITY TESTING

Define “integrity testing” as crosshole sonic logging (CSL) and thermal profile logging (TPL).

Integrity testing shall be performed as noted in the plans or as required by the Engineer. Perform

TPL testing if required in the contract. The Engineer will determine how many and which drilled piers require integrity testing. For CSL testing, do not test piers until Drilled Pier concrete cures for at least 7 days and attains a compressive strength of at least 3,000 psi.

(A) Crosshole Sonic Logging

If CSL testing is required, use a prequalified CSL Consultant to perform CSL testing and provide CSL reports. Use a CSL Operator approved as a Field Engineer (key person) for the CSL Consultant. Provide CSL reports sealed by an engineer licensed in the State of

North Carolina approved as a Project Engineer (key person) for the same CSL

Consultant.

(1) CSL Testing

Perform CSL testing in accordance with ASTM D6760. If probes for CSL testing will not pass through to the bottom of CSL tubes, the Engineer may require coring to replace inaccessible tubes. Do not begin coring until core hole size and locations are approved by the Engineer. Core at least 1.5 inches diameter holes the full length of piers. Upon completion of coring, fill holes with clean water and cover to keep out debris. Perform CSL testing in core holes instead of inaccessible tubes.

For piers with 4 or 5 CSL tubes, test all tube pairs. For piers with 6 or more CSL tubes, test all adjacent tube pairs around spiral reinforcing steel and at least 50% of remaining tube pairs selected by the Engineer. Record CSL data at depth intervals of 2.5 inches or less from the bottom of CSL tubes to top of piers.

(2) CSL Testing

Submit each CSL report within 7 days of completing CSL testing. Include the following in CSL reports:

(a) Title Sheet

(i) Department’s TIP number and WBS element number

(ii) Project description

(iii) County

(iv) Bridge station number

(v) Pier location

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(vi) Personnel

(vii) Report date

(b) Introduction

(c) Site and Subsurface Conditions (including water table elevation)

(d) Pier Details

(i) Pier and casing diameters, lengths and elevations

(ii) Drilled Pier concrete compressive strength

(iii) Installation methods including use of casings, slurry, pumps, tremies, dry or wet placement of concrete, etc.

(e) CSL Results

(i) Logs with plots of signal arrival times and energy vs. depth for all tube pairs tested

(f) Summary/Conclusions

(i) Table of first arrival time (FAT) increases greater than 30% of the local average FAT value with corresponding locations (tube pair(s) and depth ranges) for all tube pairs tested

(ii) Table of relative energy reductions 9 dB greater than the local average relative energy value with corresponding locations (tube pair(s) and depth ranges) for all tube pairs tested

(iii) List of suspected anomalies with corresponding locations (tube pair(s) and depth ranges)

(g) Attachments

(i) Boring log(s)

(ii) Field inspection forms and concrete curves (from Engineer)

(iii) CSL tube locations, elevations, lengths and identifications

(iv) CSL hardware model and software version information

(v) PDF copy of all CSL data

(B) Drilled Pier Evaluation

Define “drilled pier evaluation” as any additional testing, excavation or coring following integrity testing. Based on concrete placement and CSL results, the Engineer will determine if drilled piers require evaluation within 7 days of receiving CSL reports, in accordance with Table 411-4.

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TABLE 411-4

DRILLED PIER EVALUATION CRITERIA

FAT Increase Relative Energy Reduction Evaluation Required?

≤ 30% ≤ 9 dB No

> 30% ≤ 9 dB Yes

≤ 30% > 9 dB Yes

> 30% > 9 dB Yes

If drilled pier evaluation is necessary, use one or more of the following methods, or any other methods approved by the Engineer to investigate the pier.

(1) CSL Testing

Use CSL testing as described in Subarticle 511-5(A) and perform testing with probes vertically offset in CSL tubes. CSL offset data will typically be required for all locations (tube pair and depth) where first arrival time increases are greater than 30% and relative energy reduction exceeds 9 dB. Record offset data at depths, intervals and angles needed to completely delineate anomalies.

Provide CSL reports that meet Subarticle 411-5(A)(2). When CSL offset data is required, perform tomographic analysis and provide 3 dimensional color coded tomographic images of piers showing locations and sizes of anomalies.

(2) Excavation

Excavate around piers and remove permanent casing as needed to expose Drilled

Pier concrete. Do not damage piers when excavating or removing casings. The

Engineer will determine the portions of piers to expose.

(3) Coring

Core piers and provide PQ size cores that meet ASTM D2113. The Engineer will determine the number, location and depth of core holes required based on CSL and Tomographic Analysis. Handle, log and store concrete cores with methods acceptable to the Engineer. Use a consultant with an engineer licensed in the

State of North Carolina to log cores and use a qualified NCDOT laboratory to test strength of the selected core specimens.

Submit to the Engineer the investigation results in a drilled pier evaluation report sealed by an engineer licensed in the State of North Carolina for review and approval.

(C) Drilled Pier Remediation

If the Engineer determines a drilled pier is unacceptable, remediation is required.

Remediation may include, but is not limited to hydroblasting and pressure grouting, utilizing micropiles within the drilled pier to transfer load above and below a defect, removing part or all of unacceptable drilled piers, modifying drilled pier design or providing replacement or additional drilled piers, micropiles, and/or driven piles within a pier footing or bent cap. Submit a drilled pier remediation report including the working drawings and design calculations for acceptance in accordance with Article 105-2.

Ensure the drilled pier remediation report is designed, detailed and sealed by an engineer licensed in the State of North Carolina. Do not begin remediation work until remediation

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plans are approved by the Engineer. When repairing unacceptable piers, perform post repair verification testing to gauge success of the repair.

411-6 DRILLED PIER ACCEPTANCE

Drilled pier acceptance is based in part on the following criteria:

(A) Temporary casings and drilling tools are removed from the drilled pier excavation or the

Engineer determines that a temporary casing may remain in the excavation.

(B) Drilled Pier concrete is properly placed and does not have any evidence of segregation, intrusions, contamination, structural damage or inadequate consolidation (honeycombing) and meets compressive strength required in Table 1000-1.

(C) Center of pier is within 3 inches of plan location and 2% of plumb. Top of pier is within 1 inch above and 3 inches below the elevation shown in the plans or approved by the

Engineer.

(D) Rebar cage is properly placed and top and center of cage is within tolerances for center of pier. Tip of permanent casing does not extend below the elevation noted in the plans or approved by the Engineer.

(E) CSL report meeting Subarticle 411-5(A)(2).

(F) Drilled pier evaluation report meeting Subarticle 411-5(B).

(G) Drilled pier remediation report meeting Subarticle 411-5(C).

Do not grout CSL tubes or core holes, backfill around a pier or perform any work on a drilled pier until the Engineer accepts the pier. If the drilled pier is accepted by the Engineer, dewater and grout CSL tubes and core holes, and backfill around the pier with approved material to finished grade. No extension of completion date or time will be allowed for remediation of unacceptable drilled piers or post repair testing.

411-7 MEASUREMENT AND PAYMENT

____ Dia. Drilled Piers in Soil, ____ Dia. Drilled Piers Not in Soil and ____ Dia. Drill Piers will be measured and paid in linear feet. Acceptable drilled piers will be measured as the difference between the specified top of pier and pier tip elevations or revised elevations approved by the Engineer.

For bents with a not in soil pay item shown in the plans, drilled piers will be paid as ____ Dia.

Drilled Piers in Soil and ____ Dia. Drilled Piers Not in Soil. Define “not in soil” as material with a rock auger penetration rate of less than 2 inches per 5 minutes of drilling at full crowd force. When not in soil is encountered, seams, voids and weathered rock less than 3 feet thick with a rock auger penetration rate of greater than 2 inches per 5 minutes of drilling at full crowd force will be paid at the contract unit price for ____ Dia. Drilled Piers Not in Soil. Seams, voids and weathered rock greater than 3 feet thick will be paid at the contract unit price for ____ Dia.

Drilled Piers in Soil where not in soil is no longer encountered. For bents with a not in soil pay item shown in the plans, drilled piers through air or water will be paid at the contract unit price for ____ Dia. Drilled Piers in Soil.

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For bents without a not in soil pay item shown in the plans, drilled piers will be paid as

____ Dia. Drill Piers. The contract unit price for ____ Dia. Drilled Piers will be full compensation for drilling through any materials encountered.

The contract unit prices for ____ Dia. Drilled Piers in Soil, ____ Dia. Drilled Piers Not in Soil and ____ Dia. Drill Piers will also be full compensation for spoils and slurry containment and disposal, supplying and placing Drilled Pier concrete, material and testing requirements in

Subarticle 411-2(E), temporary casing and slurry construction including a slurry manufacturer representative and overreaming and enlarging piers and any concrete removal, miscellaneous grading and excavation. No additional payment will be made for excess Drilled Pier concrete due to caving or sloughing holes or telescoping casings.

Reinforcing steel will be measured and paid in accordance with Article 425-6.

Permanent Steel Casing for ____ Dia. Drilled Pier will be measured and paid in linear feet.

Permanent casings will only be paid for when required by the Engineer or shown in the plans.

Permanent casings will be measured as the difference between the ground line or specified top of pier elevation, whichever is higher, and the specified permanent casing tip elevation or revised elevation approved by the Engineer. If a permanent casing cannot be installed to the casing tip elevation shown in the plans, up to 3 feet of casing cut-off will be paid at the contract unit price for Permanent Steel Casing for ____ Dia. Drilled Pier.

SID Inspections will be measured and paid in units of each. SID Inspections will be measured as one per pier. The contract unit price for SID Inspections will be full compensation for inspecting holes with the SID the first time. No additional payment will be made for subsequent inspections of the same hole.

The Contractor is responsible for any damage to the SID equipment due to the Contractor’s fault or negligence. Replace any damaged equipment at no additional cost to the Department.

SPT Testing will be measured and paid in units of each. SPT Testing will be measured as the number of standard penetration tests performed except no payment will be made for SPT Testing to determine if temporary casing is necessary.

CSL Testing will be measured and paid in units of each. CSL Testing will be measured as one per pier. The contract unit price for CSL Testing will be full compensation for performing initial

CSL testing and providing CSL reports. Subsequent CSL testing of and CSL reports for the same pier will be considered further investigation. No separate payment will be made for CSL tubes. CSL tubes including coring for inaccessible tubes and grouting will be incidental to the contract unit prices for drilled piers.

No payment will be made for stuck temporary casings that cannot be removed from drilled pier excavations or additional drilled pier length and reinforcing steel required due to temporary casings that remain in excavations. Drilled pier evaluations of piers that are acceptable based on drilled pier evaluation reports will be paid as extra work in accordance with Article 104-7. No payment will be made for drilled pier evaluations of unacceptable drilled piers, drilled pier

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remediation or post repair testing.

Payment will be made under:

Pay Item Pay Unit

____ Dia. Drilled Piers in Soil Linear Foot

____ Dia. Drilled Piers Not in Soil Linear Foot

____ Dia. Drilled Piers Linear Foot

Permanent Steel Casing for ____ Dia. Drilled Piers Linear Foot

SID Inspections Each

SPT Testing Each

CSL Testing Each

SHANE C CLARK

29869

10/01/2026

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