AMND_0002 Spec 31 68 13.00 25.pdf

Hills Creek Rock Removal and Reinforcement

SECTION TABLE OF CONTENTS

DIVISION 31 - EARTHWORK

SECTION 31 68 13.00 25

SOIL AND ROCK ANCHORS

PART 1 GENERAL

1.1 SUMMARY OF WORK

1.2 REFERENCES

1.3 DEFINITIONS

1.3.1 Rock Slope

1.3.2 Permanent Rock Stabilization

1.3.3 Temporary Rock Stabilization

1.3.4 Rock Anchor

1.3.5 Wire Rope Anchor

1.3.6 Drain Hole

1.3.7 Rockfall Mesh

1.3.8 Scaling

1.3.9 Clearing and Grubbing

1.3.10 Concrete Protection

1.3.11 Inspection Assistance

1.3.12 Demonstration Test Anchor

1.3.13 Qualified Engineer

1.4 SYSTEM DESCRIPTION

1.5 SUBMITTALS

1.6 QUALITY ASSURANCE

1.6.1 Fabricator Qualifications

1.6.2 Installer Qualifications

1.6.3 Rope Access Work Plan

1.6.4 Rock Reinforcement Installation Plan

1.7 DELIVERY, STORAGE, AND HANDLING

1.8 SITE CONDITIONS

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Prestressing Steel

2.1.2 Steel Pipe

2.1.3 Steel Tube

2.1.4 Epoxy-Coated Steel Bars

2.1.5 Rockfall Mesh

2.1.6 Slotted Drain Pipe

2.1.7 Lubricant

2.2 MANUFACTURED UNITS

2.2.1 Mesh Spike Plate

2.2.2 Anchor Bearing Plate

2.2.3 Prestressing Steel Couplers

2.2.4 Centralizers

2.3 EQUIPMENT

2.3.1 Drilling Equipment

2.3.2 Grouting Equipment

SECTION 31 68 13.00 25 Page 1

2.3.2.1 Grout Mixer

2.3.2.2 Grout Pump

2.3.3 Testing Equipment

2.3.4 Stressing Equipment

2.3.5 Torque Wrench

2.4 GROUT

2.4.1 Cement

2.4.2 Water

2.4.3 Aggregates

2.4.4 Admixtures.

2.4.5 Grout for Anchors

2.4.5.1 Cement Grout

2.4.6 Sand-Cement Grout

2.4.7 Grout for Anchor Pads

2.5 ANCHOR FABRICATION

2.5.1 General

2.5.2 Tendon

2.5.3 Vent Tubes

2.5.4 Grout Tubes

2.5.5 Corrosion Protection

2.5.6 Free Stressing Length Encapsulation

2.6 TESTS, INSPECTIONS, AND VERIFICATIONS

PART 3 EXECUTION

3.1 SCALING

3.2 INSPECTION ASSISTANCE

3.3 DRILLING HOLES

3.3.1 General

3.3.2 Drilling Through Existing Rock Reinforcement

3.3.3 Casing

3.3.4 Drilling in Rock

3.3.5 Drain Holes

3.3.6 Records

3.3.7 Alignment

3.3.7.1 Tolerances

3.4 INSTALLATION OF ANCHORS

3.4.1 General

3.4.2 Placing

3.4.3 Cement Grouted Rock Anchors

3.4.4 Anchorage Installation

3.5 INSTALLATION OF ROCKFALL MESH

3.6 STRESSING

3.6.1 General Requirements

3.6.2 Lock-off

3.7 FIELD QUALITY CONTROL

3.7.1 Performance Test

3.7.2 Proof Test

3.7.3 Driller Logs

3.7.4 Installation Records

3.8 ACCEPTANCE

3.8.1 General

3.8.1.1 Creep

3.8.1.2 Movement

3.8.1.2.1 Minimum Apparent Free Length

3.8.1.2.2 Maximum Apparent Free Length

3.8.1.3 Initial Lift-Off Reading

3.8.2 Replacement of Rejected Anchors

SECTION 31 68 13.00 25 Page 2

-- End of Section Table of Contents --

SECTION 31 68 13.00 25 Page 3

SECTION 31 68 13.00 25

SOIL AND ROCK ANCHORS

PART 1 GENERAL

1.1 SUMMARY OF WORK

a. This Section specifies the general requirements for evaluating rock wall conditions, scaling rock surfaces, and furnishing and installing rock reinforcement and stabilization elements.

b. Notwithstanding any other provisions of this Contract or any Contracts or agreements between the Contractor and other entities regarding the project, the Contractor must perform all work so as to minimize the exposure of personnel and equipment to hazardous and potentially hazardous conditions. The Contractor must take every necessary precaution, including, among others, additional scaling and installation of temporary rock stabilization, whether directed by the Contracting Officer (CO) for measurement and payment or not. Nothing in these Specifications is to be construed as relieving the Contractor from sole responsibility for the safety of the work and or all liability for injuries or deaths to persons or damages to property.

1.2 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.

AMERICAN CONCRETE INSTITUTE (ACI)

ACI 301 (2016) Specifications for Structural Concrete

ASTM INTERNATIONAL (ASTM)

ASTM A36/A36M (2019) Standard Specification for Carbon Structural Steel

ASTM A53/A53M (2022) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless

ASTM A123/A123M (2017) Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products

ASTM A500/A500M (2021a) Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes

ASTM A615/A615M (2022) Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement

SECTION 31 68 13.00 25 Page 4

ASTM A775/A775M (2022) Standard Specification for Epoxy-Coated Steel Reinforcing Bars

ASTM C33/C33M (2018) Standard Specification for Concrete Aggregates

ASTM C109/C109M (2021) Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or (50-mm) Cube Specimens)

ASTM C150/C150M (2022) Standard Specification for Portland Cement

ASTM C1107/C1107M (2020) Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink)

ASTM D1785 (2015; E 2018) Standard Specification for Poly(Vinyl Chloride) (PVC), Plastic Pipe, Schedules 40, 80, and 120

POST-TENSIONING INSTITUTE (PTI)

PTI DC35.1 (2014) Recommendations for Prestressed Rock and Soil Anchors

PTI TAB.1 (2006) Post-Tensioning Manual

U.S. ARMY CORPS OF ENGINEERS (USACE)

EM 385-1-1 (2014) Safety -- Safety and Health Requirements Manual

1.3 DEFINITIONS

The following definitions are in addition to those given in PTI DC35.1 , Section 2.0:

1.3.1 Rock Slope

The Rock Slope refers to the rock surfaces which will be stabilized as defined in the Contract drawings.

1.3.2 Permanent Rock Stabilization

Permanent Rock Stabilization refers to the system of installed elements that are intended to provide long-term support to stabilize the existing slopes and rock excavation, and provide protection to personnel and facilities from rockfall hazards as defined in the Contract drawings.

1.3.3 Temporary Rock Stabilization

Temporary Rock Stabilization is defined as any remedial measures or rock support installed or constructed by the Contractor for the purpose of worker safety, convenience, or expeditious performance of subsequent work under this Contract or Contract activity for others at the site.

Temporary Rock Stabilization may include, but is not limited to rock dowels, rock bolts, mine straps, wire mesh, split sets, shoring, chain

SECTION 31 68 13.00 25 Page 5 link fencing or rock catchments or barriers. Temporary Rock Stabilization is considered incidental to the work and will not be measured for payment.

1.3.4 Rock Anchor

A Rock Anchor is a threaded steel bar inserted in a drilled hole and encapsulated with grout and a free-stressing length to apply a tensioning force. Rock Anchors must be installed with end hardware, bearing plates, washers, and nuts as shown on the Contract drawings or as directed or approved by the CO. Rock Anchors are intended to serve as rock reinforcement elements and are considered to be part of the Permanent Rock Stabilization.

1.3.5 Wire Rope Anchor

A Wire Rope anchor is a steel wire strand anchor inserted in a drilled hole and fully encapsulated with grout for the purposes of anchoring the boundaries and corners of the Rockfall Mesh.

1.3.6 Drain Hole

A Drain Hole is a drilled hole designed to intercept and drain hydraulic pressure from water-filled discontinuities within the rock mass.

1.3.7 Rockfall Mesh

Rockfall Mesh is the woven steel wire mesh to be installed on the Rock Slope as part of the Permanent Rock Stabilization.

1.3.8 Scaling

Scaling is defined as the mechanical or manual removal of detached, loose or potentially detached or loose rock and materials from the Rock Slope.

Scaling must be performed as directed or approved by the CO.

1.3.9 Clearing and Grubbing

The removal of vegetation, trees, and debris from the rock slope to facilitate installation of Permanent Rock Stabilization. Clearing and grubbing must be performed as directed or approved by the CO.

1.3.10 Concrete Protection

Concrete Protection refers to the necessary materials and methods necessary to protect existing concrete and appurtenant structures from damage due to construction activities. Concrete Protection may be achieved by covering existing structures with impact resistant materials such crane pads, blast mats, or similar.

1.3.11 Inspection Assistance

Inspection Assistance refers to the means and methods necessary to facilitate inspection of any aspect of the work by the Government. The Contractor is not required to provide vehicular transport.

1.3.12 Demonstration Test Anchor

An anchor which is tested to verify design assumptions and installation practices.

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1.3.13 Qualified Engineer

A Qualified Engineer is an engineer with at least five years experience in installing and testing rock anchors with a current Professional Engineer (PE) license.

1.4 SYSTEM DESCRIPTION

Prior to commencing any work, the Contractor, including all field personnel to be involved in installation of the Temporary and Permanent Rock Stabilization must meet with the CO to review the drawings and specifications, work plans, and submittals. Work may commence upon approval of the preconstruction submittals and procedures described in paragraph SUBMITTALS and after the conduct of the Preparatory Meeting.

1.5 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. Submit the following in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Installer Qualifications; G ,DG

Rope Access Work Plan; G ,DG

Rock Reinforcement Installation Plan; G ,DG

Equipment; G,DG

SD-03 Product Data

Fabricator Qualifications; G ,DG

SD-06 Test Reports

Grout Testing; G,DG

Prestressing Steel; G,DG

Stressing Equipment and Pressure Gauge Calibration; G ,DG

Anchor Performance Tests; G ,DG

Anchor Proof Tests; G,DG

SD-07 Certificates

Prestressing Steel; G ,DG

Epoxy-Coated Steel Bars; G ,DG

Torque Wrench Calibration; G ,DG

SD-11 Closeout Submittals

SECTION 31 68 13.00 25 Page 7

Driller Logs

Installation Records

1.6 QUALITY ASSURANCE

Submit anchor fabricator and installer qualifications for approval in accordance with paragraph SUBMITTALS. The submittals must, where applicable, identify individuals who will be working on this Contract and their relevant experience. No changes will be made in approved personnel without prior approval of the CO.

1.6.1 Fabricator Qualifications

The anchors must be fabricated by a manufacturer that has been in the practice of designing and fabricating rock anchors similar in size and scope to this project for at least ten years.

1.6.2 Installer Qualifications

Submit the qualifications and experience records for approval. Experience records must identify all the individuals responsible for the anchors and must include a listing of projects of similar scope performed within the specified period along with points of contact. Qualifications prior to the installation of any anchors specified in this Section. The rock stabilization elements must be installed by a firm which is regularly engaged in the installation of rock anchors and rockfall mesh with a minimum five years experience in the installation of similar anchors on steep slopes. The superintendent must have installed rock stabilization on at least five projects of similar scope and size within the last five years. Submit resumes of all personnel involved in the installation of rock reinforcement that demonstrates these qualifications.

1.6.3 Rope Access Work Plan

a. Submit for approval, at least 30 calendar days prior to starting any work, a Rope Access Work Plan. The Rope Access Work Plan must describe all rigging, equipment, and personnel necessary to perform the work on the exposed rock slopes. If roped access is to be used, the Rope Access Work Plan must conform to standards described in governing documents of the Society of Professional Rope Access Technicians (SPRAT) and the International Rope Access Trade Association (IRATA) defined in the Section titled REFERENCES and EM 385-1-1 . The Rope Access Work Plan must designate a Competent Person with a valid SPRAT Level III Technician Certification or equivalent IRATA certification. The Competent Person must have acted as a SPRAT Level III Technician on at least three similar jobs within the last three years. The Competent Person must develop the work plan in accordance to the specified references and supervise it's implementation at the site. The Rope Access Work Plan must designate a minimum of two Level II or Level III SPRAT technicians (or IRATA equivalent), one of which designated primary and one as backup, who will act as Rope Access Lead Technicians. At least one Rope Access Lead Technician must be present onsite when any roped access is being used to perform work. Rope Access Lead Technicians must have experience acting as SPRAT Level II or III personnel on at least three similar projects within the last three years. All personnel engaged in rope access work must have a minimum SPRAT Level I Certification (or

SECTION 31 68 13.00 25 Page 8

IRATA equivalent) which is current and valid. Submit proof of required certifications for all personnel engaged in the rope access work.

Additionally, submit experience records for the designated Competent Person and Rope Access Lead Technicians.

b. The Rope Access Work Plan must include a description of the means and methods used to facilitate hands-on, close-up visual inspection of the work areas by Government personnel to include vertical and near vertical rock faces where directed and provide safe access to the work areas where fall protection is required. The Rope Access Work Plan must provide descriptions of all rigging equipment as necessary for up to two USACE personnel to access the slope at any one time and provide description for a potential rescue scenario.

1.6.4 Rock Reinforcement Installation Plan

a. Submit for approval, at least 30 calendar days prior to starting an installations; complete description, schematic drawings and data sheets of the installation procedures and materials to be used for installation of the Temporary and Permanent Rock Stabilization. The drawings must include anchor length, location and configuration of bonded and unbonded length, and centralizers; Include complete description and product specifications for every element of the Temporary and Permanent Rock Stabilization to be installed. The submittal must include information describing drilling equipment and method of drilling holes;

(1) diameter,

(2) location and length of holes;

(3) type, and length of rock anchors and associated hardware;

(4) storage and handling of materials;

(5) means of mixing and placing grout;

(6) means for preventing grout loss if encountered during drilling or anchor installation;

(7) means method for leveling the bearing plate flush with the rock face;

(8) means of protecting spillway concrete from falling rock caused by construction activities;

(9) and installation procedures for the Rockfall Mesh and associated hardware.

b. The Contractor must provide a drawing with accurate elevations and stationing of the proposed work area and a naming convention for rock anchors such that the anchors are easily locatable in the field by station and elevation. These drawings will be updated during construction and submitted as a separate submittal As-Built Drawings.

Submit a sample Installation Record that includes the location, depth, hole diameter, drilling conditions, and grouting volume injected for each installed anchor.

c. The submittal must include descriptions and details of all

SECTION 31 68 13.00 25 Page 9 materials and equipment used to facilitate access to the rock faces for installation of Temporary and Permanent Rock Stabilization to include drilling, grouting and testing equipment. The submittal must include detailed descriptions of all scaling, washing, drilling, borehole flushing, and installation and erection equipment to be used for the work. Additionally, the submittal must include a description and schematic drawing of the load frame capable of maintaining the maximum test load without fracturing the surrounding rock. Submit configuration and data sheets and calibration certificates for testing equipment including the hydraulic jack, pressure gauge and measurement device to be used for load testing of the rock anchors. Anchor testing must be performed by a personnel with a minimum three years experience in the testing of rock anchors. The personnel responsible for anchor testing must have worked on three projects of similar size and scope within the last three years. Submit the name(s) of personnel that will perform the testing with a description of applicable anchor testing experience at least 30 days prior to testing any anchors.

1.7 DELIVERY, STORAGE, AND HANDLING

Materials must be suitably wrapped, packaged or covered at the factory or shop to prevent being affected by dirt, water, oil, grease, and rust.

Protect materials against abrasion or damage during shipment and handling. Place materials stored at the site above ground on a well supported platform and covered with plastic or other approved material.

Materials must be protected from adjacent construction operations.

Grounding of welding leads to prestressing steel will not be permitted.

Reject and remove from the site prestressing steel which is damaged by abrasion, cuts, nicks, heavy corrosions, pitting, welds or weld spatter.

Inspect tendons prior to insertion into anchor holes for damage to corrosion protection. Any such damage must be repaired in a manner recommended by the tendon manufacturer and approved by the CO.

1.8 SITE CONDITIONS

Current site conditions are shown on the drawings. While the drawings and indicative of the site conditions, local variations which may be encountered include, but are not limited to, classification and thickness of rock strata, fractures, and other discontinuities in the rock structure, and variation in groundwater conditions. Such variations will not be considered as differing materially within the purview of FAR 36.502 Differing Site Conditions. The Contractor is responsible for verifying the location of all utilities that may be affected by construction or the installation of the anchors.

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Prestressing Steel

Submit certified test reports for each heat or lot of prestressing steel with materials delivered to the site. Submit five copies of mill reports and five copies of a certificate from the manufacturer stating chemical properties, ultimate strengths, yield strengths, modulus of elasticity, and any other physical properties needed for the required computations, for the type of steel furnished. Digital certification is permitted.

SECTION 31 68 13.00 25 Page 10

2.1.2 Steel Pipe

ASTM A53/A53M, Type E or S, Grade B.

2.1.3 Steel Tube

ASTM A500/A500M

2.1.4 Epoxy-Coated Steel Bars

1-1/4 inch diameter (#10), Grade 75, epoxy-coated, threaded bars conforming to ASTM A615/A615M . Corrosion protection must conform to coating requirements of PTI DC35.1 Type II anchors and ASTM A775/A775M with eight mils minimum thickness. Submit written certification for coating material and coated bars with the delivery of the bars. Coating at the anchorage end may be omitted over the length provided for threading the nut against the bearing plate.

2.1.5 Rockfall Mesh

The mesh must be hot dipped galvanized or epoxy/polyester resin coated corrosion-resistant steel wire mesh constructed from high strength wire with a minimum diameter of 0.118 inch specifically for rock stabilization.

The wire mesh must have an opening not to exceed 2.56 inches measured as the diameter of the largest sphere that would pass through the mesh opening. The mesh must have a minimum tensile strength of 10.2 kips/linear foot and the tensile resistance of a single wire must be a minimum 2.8 kips. All components associated with the Rockfall Mesh for installation, attachment splicing, anchoring and connection of panels or connection of panels to the rock face must be designed by the manufacturer for that purpose and compatible with other elements of the rock support and rock stabilization. The top horizontal support rope and boundary ropes must be a minimum 0.75-inch diameter conforming to the mesh manufacturer's recommendations. Wire rope anchors must be a minimum 0.75-inch diameter conforming to mesh manufacturer's recommendations. The Rockfall Mesh must include all labor, hardware, border cable, splicing materials and equipment associated with the installation of the mesh including the wire rope anchors. exclusive of rock anchor s, which must be measured for payment separately.

2.1.6 Slotted Drain Pipe

Slotted drain pipe must be a two inch diameter, Schedule eighty slotted polyvinyl chloride (PVC) well casing. The drain pipe must have 0.05-inch wide slots along the full length of the pipe. Provide all slotted drain pipes with an end cap manufactured by the same company as the slotted drain pipe.

2.1.7 Lubricant

Lubricant for threads and washers must be molybdenum disulfide base lubricant or as recommended by the rock anchor manufacturer.

2.2 MANUFACTURED UNITS

2.2.1 Mesh Spike Plate

The bearing plate used to secure mesh to the slope must be a

SECTION 31 68 13.00 25 Page 11 diamond-shaped spike plate designed specifically for use with anchored rockfall mesh systems. The bearing plate must be hot dipped galvanized, per ASTM A123/A123M The dimensions of the bearing plate must be approximately 26 inches long by 12 inches wide with a minimum thickness of

0.25 inches and a hole diameter of 50 mm. The plate must have a longitudinal bending resistance equal to or greater than 540 lb-ft.

2.2.2 Anchor Bearing Plate

The anchor bearing plate must be square 12 inches by 12 inches by one inch thick galvanized steel conforming to ASTM A36/A36M. The anchorage devices must conform to the static strength requirements of Section 3.1.6 (1) and Section 3.1.8 (1) and (2) of PTI TAB.1 . Wedges must be designed to not cause premature failure of the prestressing steel due to notching or pinching. Provide special wedges as required for epoxy coated strand.

Removal of epoxy coating to permit use of standard wedges will not be permitted. Threaded anchorage items for epoxy coated bars must be designed to fit over the epoxy coating and maintain the capacity of the prestressing steel.

2.2.3 Prestressing Steel Couplers

Prestressing steel couplers for bars must be capable of developing 100 percent of the minimum specified ultimate tensile strength of the prestressing steel.

2.2.4 Centralizers

Centralizers must be fabricated from plastic, steel or other approved material which is nondetrimental to the prestressing steel. Wood must not be used. The centralizer must be able to support the tendon in the drill hole and position the tendon so a minimum of 0.5 inch of grout cover is provided. Centralizers must permit grout to freely flow up the drill hole.

2.3 EQUIPMENT

The Contractor's Quality Control manager must verify that the equipment used on site is the same as the equipment submitted for approval. Submit catalog cuts, brochures, or other descriptive literature describing the equipment to be used for drilling, grouting, handling, installing and testing the rock anchors. Submit sketches, drawings or details showing the access and temporary supports where required for the drilling equipment and stressing frames. Provide descriptions of stressing jacks, gages, dynamometers, load cells, or other devices for measuring stressing load, certified calibration records for each set of jacking equipment, and current testing curves for stress measurement gages which show that gages have been calibrated for the jacks for which they are used 30 days prior to the start of the testing operations.

2.3.1 Drilling Equipment

Provide drilling equipment suitable for advancing the drill tools to the depths and at the alignment specified.

2.3.2 Grouting Equipment

2.3.2.1 Grout Mixer

The grout mixer must be a high-speed, high-shear, colloidal type grout

SECTION 31 68 13.00 25 Page 12 mixer capable of continuous mechanical mixing that will produce uniform and thoroughly mixed grout which is free of lumps and undispersed cement.

The mixer must be equipped with a suitable water and admixture measuring device calibrated to read in cubic feet and tenths and so designed that after each delivery the hands can be conveniently set back to zero.

2.3.2.2 Grout Pump

The grout pump must be of the positive displacement type, and must be capable of pumping at all flow rates below 20 gpm, must be capable of pumping at the pressure of at least 50 psi at zero flow rate. For neat cement grout, the pump must have a screen with 0.125 inch maximum clearance to sieve the grout before being introduced into the pump.

Screens are not required for shear type mixers. Make available a pump which is capable of pumping both neat cement grout mixes and sanded grout mixes. The pumping equipment must have a pressure gage capable of measuring pressures of at least 150 psi or twice the required grout pressure, whichever is greater.

2.3.3 Testing Equipment

Provide testing equipment consisting of a hydraulic jack with calibrated pressure gage for applying the load and a dial gage or vernier scale to measure anchor movement. The ram travel of the stressing equipment must be not less than the theoretical elastic elongation of the total anchor length at the maximum Test Load. The pressure gage must be graduated in 100 psi increments. The Stressing Equipment and Pressure Gauge Calibration must have been completed as a unit no more than 30 calendar days prior to commencing work under this Contract and at six-month intervals throughout the period of use. The movement measuring device must have a minimum travel equal to the theoretical elastic elongation of the total anchor length at the maximum Test Load without resetting the device.

2.3.4 Stressing Equipment

Stressing equipment must be hydraulically operated and must have a capacity sufficient to stress the anchors to the required Test Loads within the rated capacity in one stroke. Pumps must be capable of applying each load increment in less than 60 seconds and must be capable of maintaining the hydraulic pressure within 50 psi. The equipment must permit stressing of the tendon in increments and raising or lowering the load in the tendon. The equipment must be calibrated with an accuracy of plus or minus two percent and the calibration certificate and graphs must be available at the site. The production gage must have graduations of 100 psi or less. A second certified gage must be maintained for periodic verification of the production gage. A dial gage or approved device must be provided to measure total tendon elongation at each load increment to the nearest 0.001 inch. The dial gage must be capable of measuring the entire anchor movement without being reset. Calibration of gages must be verified no more than 30 calendar days prior to commencing work under this Contract and at six month intervals throughout the period of use.

2.3.5 Torque Wrench

Torque wrenches may be manual or pneumatic provided they are of sufficient capacity for the capacities indicated on the Contract plans. Provide appropriate sockets for the nuts to be tensioned. Submit Torque Wrench Calibration certificate as part of the Rock Reinforcement Installation Plan.

SECTION 31 68 13.00 25 Page 13

2.4 GROUT

2.4.1 Cement

ASTM C150/C150M, Type I, II, III or V.

2.4.2 Water

Provide fresh, clean, potable water free from injurious amounts of sewage, oil, acid, alkali, salts, or organic matter.

2.4.3 Aggregates

Fine aggregate for sand-cement grout must conform to ACI 301 and ASTM C33/C33M for grout for backfilling holes. Aggregates must not contain substances which may be deleteriously reactive with alkalis in the cement.

2.4.4 Admixtures.

Admixtures which control bleed, improve flowability, reduce water content and retard set may be used in the grout subject to the approval of the CO. Any admixtures used must be compatible with the prestressing steel and must be mixed in accordance with the manufacturer's recommendations.

2.4.5 Grout for Anchors

2.4.5.1 Cement Grout

Grout for grouting anchors must consist of a homogenous, pumpable, stable mixture of portland cement and water. Submit the proposed mix design to the CO for approval and results of compressive strength testing. The water content must be the minimum necessary for proper placement but the water-cement ratio must not exceed 0.45 by weight. Final proportions of materials must be based on results of tests made on sample mixtures of grout. The minimum compressive strength of two inch cubes, molded, cured, and tested in accordance with ASTM C109/C109M, must be 4,000 psi at the time of stressing. The Contractor is responsible for taking, curing, and breaking of grout test cubes for determining mix design, and all testing must be done by an independent laboratory approved by the CO. Submit Grout Testing results reporting compressive strength testing results prior beginning work as part of the Rock Reinforcement Installation Plan. Submit subsequent compressive strength tests on the frequency of every 50 installed rock anchors.

2.4.6 Sand-Cement Grout

Grout for holes that experience grout loss and for backfilling holes which are abandoned must consist of a mixture of portland cement, fine aggregate and water. The grout must consist of one part portland cement and two parts fine aggregate by volume, mixed with sufficient water to provide a uniform consistency. Submit the proposed mix design to the CO for approval .

The water content must be the minimum necessary for proper placement.

Final proportions of materials must be based on results of tests made on sample mixtures of grout. The minimum compressive strength of two inch cubes, molded, cured, and tested in accordance with ASTM C109/C109M, must be 4,000 psi at 28 days. The Contractor is responsible for taking, curing, and breaking of grout test cubes for determining mix design, and all testing must be done by an independent laboratory approved by the CO.

SECTION 31 68 13.00 25 Page 14

2.4.7 Grout for Anchor Pads

Use nonshrink grout conforming to ASTM C1107/C1107M for leveling bearing plates.

2.5 ANCHOR FABRICATION

2.5.1 General

Fabrication of the anchors must be as recommended by the suppliers.

Anchors must be completely assembled with all grout and vent tubes and corrosion protection prior to insertion into the hole. Fabricated anchors must be protected, transported and stored in a manner to prevent contamination or damage to any components.

2.5.2 Tendon

Tendon material must be unblemished and free of pitting, nicks, grease, or injurious defects. When required to maintain the tendon location within the hole, provide centralizers at a maximum of 10 foot intervals center-to-center throughout the bond length. The entire bond length of the tendon must be free of dirt, lubricants, loose rust, corrosion-inhibiting coatings or other contaminants.

2.5.3 Vent Tubes

Vent tubes used during grouting operations, if necessary, must be any appropriate type for the job, as recommended by the supplier of the anchors.

2.5.4 Grout Tubes

Grout tubes must be polyethylene tubing or as recommended by the anchor manufacturer and approved by the CO. Inside diameter of grout tubes must be adequate to fully grout the entire hole.

2.5.5 Corrosion Protection

Corrosion protection must be provided for the entire anchor and must include anchorages covers and trumpets filled with corrosion inhibiting compound or grout and encapsulation of the free stressing length and bond length.

2.5.6 Free Stressing Length Encapsulation

Encapsulation for free stressing length must consist of a sheath of smooth polyethylene tubing, minimum wall thickness 0.06 inch; smooth polypropylene tubing, minimum wall thickness 0.06 inch; or smooth PVC tubing, minimum wall thickness 0.04 inch. Sheath for bars may be heat shrinkable sleeve with a minimum thickness of 0.024 inch. Free stressing length encapsulation must extend at least four inches into the trumpet, but must not contact the bearing plate during testing and stressing of the tendon.

2.6 TESTS, INSPECTIONS, AND VERIFICATIONS

Perform required material tests, on prestressing steel and accessories, by an approved laboratory to demonstrate that the materials are in

SECTION 31 68 13.00 25 Page 15 conformance with the specifications. Test grout in accordance with ASTM C109/C109M. Laboratory grout tests must be performed by a USACE Materials and Testing Center validated laboratory. These tests must be at the Contractor's expense. Furnish to the CO prestressing steel test results prior to beginning fabrication of any anchors and within 24 hours of testing.

PART 3 EXECUTION

3.1 SCALING

Before scaling, install Concrete Protection as defined above to minimize damage to concrete surfaces. Ensure that existing Government structures are protected from falling rock impact or other construction activities.

Any damage to existing concrete caused by the Contractor's construction activities must be repaired at no cost to the Government. Scale the rock slope within the work limits as directed by the CO. Cut and remove existing rockfall mesh as directed by the CO. Scaling must proceed in a top down sequence. Following Scaling, areas will be identified where the Contractor must provide inspection assistance for the CO and Government personnel to inspect, map and perform assessment of rock conditions as defined in the Rope Access Work Plan. Notwithstanding the results of the assessment by the CO, the Contractor must be responsible for the safety of the work area defined within the work limits of this Contract. Remove trees on the slope within the areas where Permanent Rock Stabilization will be installed by cutting such that stumps are six inches or less in height as measured on the upslope side or such that the remaining stumps do not interfere with installation or performance of the Permanent Rock Stabilization. Remove all rock and vegetation debris caused by scaling or other construction activities from the site.

3.2 INSPECTION ASSISTANCE

Following scaling, provide Inspection Assistance to allow the Contracting Officer or Government to access the vertical or near-vertical rock face(s) and within the proximity of the rock slope where fall protection is required under the provisions of EM 385-1-1 , OSHA and the Access Work Plan.

Inspection Assistance may be achieved by any approved combination of cranes,tie offs, man baskets, man lifts, man cages and roped access. The Contractor must provide safety supervision of USACE personnel performing inspection via rope access by SPRAT or IRATA certified personnel to include at a minimum one Level II Rope Access Technician and one Level I Rope AccessTechnician. The CO must provide a 48 hour advance notice when Inspection Assistance is required.

3.3 DRILLING HOLES

3.3.1 General

Holes must be drilled at the locations and inclinations shown and to the depths and diameters indicated on the drawings or as directed by the CO.

Verify and mark the locations of the work limits for installation of the Permanent Rock Stabilization prior to beginning work. The locations of the holes may be changed only as approved by the CO. Unless otherwise specified, the Contractor must determine the drilling method to be used.

No holes must be drilled within 50 feet of a grouted hole until the grout has set at least 24 hours. Care must be taken while drilling to avoid damage of any kind to the existing structures. Damages of any nature will be evaluated by the CO and repairs or replacements must be made as

SECTION 31 68 13.00 25 Page 16 required. Provide a temporary plug for all holes drilled more than 10 days prior to installation of the anchor. Waste water from drilling operations must be collected and recycled or treated; it must not be discharged directly on the ground. See also Section 01 57 19.00 25 TEMPORARY

ENVIRONMENTAL CONTROLS.

3.3.2 Drilling Through Existing Rock Reinforcement

Existing rockfall mesh to remain in place except where necessary to remove small areas to facilitate drilling and installation of new rock reinforcement elements. If the Contractor detaches portions of the existing mesh from the slope for the purposes of installing new rock reinforcement, the mesh must be removed from the site.

3.3.3 Casing

If necessary, casing must be utilized for drilling through unstable rock.

Casing may not be used as a substitute for centralizers.

3.3.4 Drilling in Rock

Drill holes in rock by core drilling, rotary drilling, percussion drilling or down-the-hole hammer using equipment suitable for the intended purpose. The drilling method must not cause structural damage to existing structures. If damage is observed, the drilling method must be modified.

Overdrilling of holes by a maximum of three feet beyond the required elevation must be permitted if complete removal of cuttings and other material cannot be accomplished. If the hole is overdrilled, the tendon must be supported so that the free length corrosion protection extends the required length into the trumpet and so that the anchor can be stressed.

If the borehole collapses, repair or redrilling will be the responsibility of the Contractor at no cost to the Government.

3.3.5 Drain Holes

Drill drain holes at the locations, orientations, and depths as shown on the Contract drawings or as directed by the CO. Drill drain holes to the depths and at the orientation shown on the drawings. After drilling, flush the Drain Hole with clean water until the return water is clear and free of drill cuttings and mud. If drains are not installed immediately, tightly plug the hole and flush all holes clean immediately before installation of the drain. If the borehole collapses, repair or redrilling will be the responsibility of the Contractor at no cost to the Government.

Drain Holes will be fitted with slotted drain pipe as indicated in Paragraph SLOTTED DRAIN PIPE of this specification. End caps must be installed prior to inserting the pipe into the hole. The top six inches of the annular space must be dry-packed with shrinkage compensated grout conforming to Paragraph GROUT FOR ANCHOR PADS and the end of the drain pipe centered to force seepage to exit the slope face through the pipe.

The free-draining end of the slotted pipe must be capped with a drop-in grate as shown on the drawings and per ASTM D1785. Slotted drain pipe must extend a minimum of three inches beyond the final rock surface.

3.3.6 Records

Submit driller logs and records as specified in paragraph Driller Logs.

The presence of a Government inspector or the keeping of separate drilling records by the CO must not relieve the Contractor of the responsibility for the work specified in this paragraph. Payment will not be made for

SECTION 31 68 13.00 25 Page 17 any work for which the required records have not been furnished by the Contractor.

3.3.7 Alignment

3.3.7.1 Tolerances

The anchor hole must be located within 12 inches of the plan location.

The entry angle must be within three degrees of the specified inclination. The alignment of the drilled hole must be within three degrees of the theoretical alignment. If the hole alignment is not within these tolerances, the hole must be backfilled with cement or sand-cement grout and a new hole drilled adjacent to the rejected hole.

3.4 INSTALLATION OF ANCHORS

3.4.1 General

Install the anchors to the specified depths and tolerance. The Contractor is responsible for each drilled hole until the anchor has been installed, grouted, stressed and accepted. Holes in rock must be cleaned by pressurized air or water to remove drill cuttings and mud.

3.4.2 Placing

All the equipment used in handling and placing the anchors must be such that it does not damage or deteriorate the prestressing steel, corrosion protection, or the anchorages. Each anchor must be inspected prior to insertion into the hole. Any damage to corrosion protection must be repaired prior to insertion or, if determined by the CO to be not repairable, the anchor must be replaced. Insertion of anchors must be in accordance with PTI DC35.1 .

3.4.3 Cement Grouted Rock Anchors

Grouting equipment must be of type and capacity required for successful installation of the rock anchors. All anchors must use single stage tremie grouting to encase the anchor. Grouting must be performed by a method in accordance with PTI DC35.1 , paragraph 7.6. Grouting must commence at the bottom of the grout zone and proceed to the top of the zone. Grouting must be gravity flow.

3.4.4 Anchorage Installation

The bearing plate and nut must be installed perpendicular to the tendon, within three degrees, and centered on the tendon without bending of the stressing steel. The bearing plate must maintain a minimum of three fourths of surface area with the rock surface. Corrosion protection must be maintained intact at the anchorage and any damage must be repaired prior to stressing.

3.5 INSTALLATION OF ROCKFALL MESH

Where installed, rockfall mesh and any associated hardware must be installed according to the recommendations of the manufacturer and as directed and approved by the CO. Additional pins must be installed to supplement attachment as directed by the CO to achieve attachment to the rock surface. The Contractor must include details of the attachment and installation of rockfall mesh in the Rock Reinforcement Installation Plan

SECTION 31 68 13.00 25 Page 18 including details for splicing, boundaries, repairs, and connectors.

3.6 STRESSING

3.6.1 General Requirements

After the anchor grout has reached the specified strength , as verified by grout cube break, the anchors must be stressed. Prior to stressing, surfaces upon which the stressing equipment is resting must be clean and the stressing equipment must be aligned as nearly with the center of the hole as possible. Design, testing and lock-off loads are shown on the Contract drawings. An Alignment Load of 10 percent of the Design Load must be applied to the anchor prior to setting dial gauges. Stress the anchor in accordance with the anchor manufacturer's recommendation, subject to the approval of the CO. Determine the lock-off procedure so that the lift-off results meet the acceptance criteria specified in paragraph Acceptance. The maximum stress must never exceed 80 percent of the guaranteed ultimate strength of anchor steel. The process of stressing the anchors must be so conducted that accurate elongation of the anchor steel can at all times be recorded and compared with the computations submitted to, and accepted by the CO. Safety precautions must be taken to prevent workers from being in front of the stressing equipment during stressing. Stressing of the anchors must be performed in a sequence submitted by the Contractor for review by the CO. All stressing must be done in the presence of a representative of the CO. At no time during the stressing and testing of an anchor must the stressing equipment be disconnected from the temporary stressing head or anchor.

3.6.2 Lock-off

After completion of the all required tests, the load must be returned to the Alignment Load and the specified Lock-off Load must be applied to the anchor. A lift-off test must be made to verify the load in the anchor bar before the tendon is locked-off and the stressing equipment is removed.

The lift-off reading must be within five percent of the specified lock-off load. If the lift-off reading is not within five percent of the specified lock-off load, the anchorage must be reset and another lift-off reading must be made. This procedure must be repeated until a satisfactory lift-off reading is obtained.

3.7 FIELD QUALITY CONTROL

The first three installed anchors are designated as demonstration test anchors. Designated demonstration test anchors must be used to verify rock quality and the adequacy of the anchor design and installation procedures. During the stressing of each anchor, a record must be kept of gage pressure and of anchor elongation at each stage of stressing to the specified test or Lock-off Load, as applicable. The Test Load must not be exceeded. Provide a Qualified Engineer to evaluate the anchor test results and determine the acceptability of the anchors in accordance with the criteria indicated hereunder. Final acceptance of each anchor will be made by the CO. The Contractor must provide inspection assistance to the Government to observe all tests being performed.

3.7.1 Performance Test

Perform a performance test on the demonstration test anchors. The performance tests must consist of cyclically and incrementally loading and unloading the anchor, and must be conducted in accordance with PTI DC35.1 , SECTION 31 68 13.00 25 Page 19

Paragraph 8.3.2. During the testing of each anchor, a record must be kept of gage pressure and of anchor elongation at each stage of stressing to each Test Load required by PTI DC35.1 . Measurements of the elongation of prestressing steel must be made in accordance with PTI DC35.1 . If the total movement at the end of 10 minutes at the Test Load exceeds 0.040 inch, the Test Load must be held an additional 50 minutes and the movement readings must be taken at the interval specified in PTI DC35.1 , Paragraph

8.3.2. The total movement for the anchor must not exceed 0.08 inch between six and 60 minutes. The anchor must satisfy criteria for minimum apparent free tendon length as defined in PTI DC35.1 paragraph 8.6.2.2. Submit results of Anchor Performance Tests including plots and graphical analysis of test data, must be furnished upon acceptance of each performance tested anchor in accordance with paragraph SUBMITTALS.

3.7.2 Proof Test

Perform a proof test on all remaining installed anchors after the first three anchors are installed and pass the performance test. Proof test must consist of incrementally loading the anchor and must be conducted in accordance with PTI DC35.1 , Paragraph 8.3.3. During the testing of each anchor, a record must be kept of gage pressure and of anchor elongation at each stage of stressing to the Test Load required by PTI DC35.1 .

Measurements of the elongation of prestressing steel must be made in accordance with PTI DC35.1 . If the total movement at the end of 10 minutes at the Test Load exceeds 0.040 inch, the Test Load must be held an additional 50 minutes and the movement readings must be taken at the interval specified in PTI DC35.1 , Paragraph 8.3.3. The total movement for the anchor must not exceed 0.08 inch between six and 60 minutes. The anchor must satisfy criteria for minimum apparent free tendon length as defined in PTI DC35.1 paragraph 8.6.2.2. Submit results of Anchor Proof Tests including plots and graphical analysis of test data, must be furnished upon acceptance of each proof tested anchor in accordance with paragraph SUBMITTALS. The proof test results must be compared with similar anchors in which performance tests have been performed. If any significant variation from the proof tests occurs, the CO may require additional performance tests.

3.7.3 Driller Logs

Submit digital copies of the original handwritten driller logs within 48 hours of completion of the hole. Keep accurate driller logs and records of all work accomplished under this Contract and deliver complete, legible copies of these logs and records to the CO upon completion of the work or at such other time or times as he may be directed. All such records must be preserved in good condition and order by the Contractor until they are delivered and accepted, and the CO must have the right to examine such records at any time prior to their delivery. Submit an example drilling log as part of the Rock Reinforcement Installation Plan. The following information must be included on the logs or in the records for each hole:

a. Hole number or designation and elevation of top of hole.

b. Rock type and depth of any significant changes in lithology or color of drill cuttings.

c. Inclination of the hole.

d. Make and manufacturer's model designation of drilling equipment.

SECTION 31 68 13.00 25 Page 20

e. Dates and time when drilling operations were performed.

f. Time required for drilling each run.

g. Steel casing seat elevation, if applicable.

h. Depths and elevations at which drill water is lost and regained and amounts, if applicable.

i. Depth of bottom of hole, determined by measuring the drill steel length.

3.7.4 Installation Records

Upon completion of installation of each anchor, submit an Installation Record to the CO with bond length, free stressing length of anchor, grout mix, grouting pressure, bags of cement injected, and a report of performance test or proof test. The performance test, proof test results must include measured lengths of drill holes and anchors, the loads and elongations recorded during testing, monitoring and stressing of the anchors, and graphs of test results. In addition as-built drawings showing the completed installation of the anchors must be furnished upon completion of installation of all anchors.

3.8 ACCEPTANCE

3.8.1 General

Acceptance of anchors must be determined by the CO. The following criteria will be used in determination of the acceptability of each anchor:

3.8.1.1 Creep

Creep movement must not exceed 0.040 inch at maximum Test Load during the first 10 minutes of the performance or proof test. If the creep movement exceeds this limit, it must not exceed 0.080 inch at the maximum Test Load at the end of 60 minutes. If the creep movement exceeds 0.080 inch at the maximum Test Load at the end of 60 minutes, the anchor will be rejected.

3.8.1.2 Movement

Apparent free length must be calculated from the observed elastic movement in accordance with PTI DC35.1 , Section 8.3.2.

3.8.1.2.1 Minimum Apparent Free Length

The calculated free length must be not less than 80 percent of the designed free tendon length plus the jack length. If the anchor does not meet this criteria, the anchor must be restressed from the Alignment Load to the Test Load and the apparent free length must be recalculated. If the anchor does not meet this criteria after three attempts (original plus two restresses), the anchor will be rejected.

3.8.1.2.2 Maximum Apparent Free Length