ML102871148

7.2 Vibration Induced by Hydro Blasting Part 1

ML102871148
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Site:	Crystal River
Issue date:	02/07/2010
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References
FOIA/PA-2010-0116
Download: ML102871148 (27)

Text

A 7.2 Vibration Induced by Hydro-Blasting

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Description:==

Hydro-blasting has important advantages over chipping hammer or roto-milling to remove a concrete layer (FM 7.2 Exhibit 1). The water jet pressure that is used is nominally 20,000 psi (FM 7.9 Exhibit 2). The pressure is obtained by means of a plunger positive displacement pump. The water nozzles rotate at 500 rpm. The jet flow rate per nozzle is around 50 gallons per minute.

Damage to concrete may occur if the jet pulsation frequency is equal to a resonant frequency of any part of the containment or bays or sleeves.

Data to be collected and Analyzed:

1. Determine natural frequencies associated with the Mac & Mac and American Hydro hydro-blasting technology (FM 7.2 Exhibit 3, FM 7.2 Exhibit 4, FM 7.2 Exhibit 5, FM 7.2 Exhibit 6, and FM 7.2 Exhibit 7);

2. Measure the natural frequency of the containment building (FM 7.2 Exhibit 8);

3. Review natural frequency as calculated and reported in the FSAR for CR3 (FM 7.2 Exhibit 9);

4. FEA calculation of the natural frequency of the building (FM 7.2 Exhibit 5);

5. FEA calculation of the impulse force from the hydro-blasting machinery (FM 7.2 Exhibit 5);

6. Observation of the crack direction and crack path (FM 7.2 Exhibit 10);

7. Interviews with Progress Energy personnel present during hydro-blasting (FM7.2 Exhibit 11);

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y "* ,J 0.3 Page I of 4 Draft 1

8. Observations of phenomena that may be related to impact from the water jets (FM 7.2 Exhibit 15).

Verified Supporting Evidence:

a. Hydro-blasting pulsation due to the rotation of the injection nozzles is about 8.3Hz (equals 500 rpm). Hydro-blasting pulsation due to the positive displacement pumps is about 8.3Hz (FM 7.2 Exhibit 5). This is close to the resonant frequencies of the wall panels between buttresses of 6.4, 7.5, and 8.4 Hz (FM 7.2 Exhibit 5 page 1 of 11);

b. Frequency measurements on the building show resonant frequencies of 7.3 and 14.96 Hz (FM 7.2 Exhibit 8). They are in the same range as the hydro-blasting frequencies (FM 7.2 Exhibit 5);

c. One witness observed vibrations on containment liner during hydro-blasting (FM 7.2 Exhibit 11);

d. Vibration of the liner resulted in paint spalling on the inside of containment (FM 7.2 Exhibit 12 and FM 7.2 Exhibit 13);

e. Double parallel cracks in the concrete may indicate out-of-plane vibration of hoop sleeves (FM7.2 Exhibit 10). Vibration-induced cracking is associated with reversing of tensile loads and with multiple parallel cracks.

Verified Refuting Evidence:

a. The impulse force resulting from a 17,000psi water jet is not sufficient to excite a structure of the size of the CR3 containment (FM 7.2 Exhibit 5 page 1 of 11). Displacements are under 350 listrains and tensile stresses under 1 psi;

b. The PII calculation (FM 7.2 Exhibit 5) also agrees with a calculation done by American Hydro (FM 7.2 Exhibit 7). They also conclude that the impulse force from the water jet is minimal;

c. The first time the hydro-blasting equipment was turned on, a mock-up operation was performed. This consisted of a small 8ft wide by 6ft high area to be hydro-blasted about 10 inches deep. There are strong indications that the crack was present very early while this mock-up was being performed (FM 7.2 Exhibit 14). This would indicate that the delamination may have been present before the hydro-blasting operation started;

d. The hydro-blasting power packs are located 400 ft (far) from the reactor opening location (FM 7.2 Exhibit 2) therefore vibrations 2/7/10 " Page 2 of 4 Enrat4e c-to third Party WitI.Permission Draft 1

from the pumps themselves cannot impact the containment wall.

Discussion:

The lowest natural frequency reported in the FSAR is 4.4 Hz (FM 7.2 Exhibit 9). This agrees very well with the P11-calculated resonant frequency for swaying of the whole building of 4.43 Hz (FM 7.2 Exhibit 5 page 1 of 11).

Interviews with engineers at Mac & Mac and at American Hydro demonstrated that the two systems are similar. American Hydro has performed eight SGR opening into post-tensioned reactor building containments (seven were performed when we started this investigation and one more was done since at TMI). All were successful, demonstrating that it is possible to hydro-blast the SGR opening.

Additionally, all the literature we found on comparing the various means to perform concrete removal agree that hydro-blasting is the least damaging to the underlying structure.

The multiple "parallel" cracks seen at several locations in the structure can be explained by other mechanisms besides vibration and are not strong evidence that vibration was critical in creating the delamination.

The water pressure is listed at 20,000psi in the Mac & Mac work instruction document. However, it was determined from interviews that the actual pressure was closer to 17,000 psi when operating at CR3.

Near the end of the hydro-blasting when the water jet was impacting close to the liner plate, there are several indications of vibration induced in the liner. It was reported by Progress personnel on the inside of containment (FM 7.2 Exhibit 11) and it was concluded from analysis of cracked features in the concrete outside of containment close to the liner plate (FM 7.2 Exhibit 15). This indicates there was enough force in the water jets to induce radial displacement of the liner plate.

This can be explained because the water at that stage in the hydro-blasting is impacting on a thin (3/8 in) long (25 ft x 27 ft) plate~of steel, loosely bonded on the four sides (mostly through mechanical locking due to the plate stiffeners).

2/7/10 R" r * . , Page 3 of 4 Draft 1

There are three key discoveries leading to our refuting of this failure mode;

1. Although the vibration frequency induced by the hydro-blasting equipment is in the same range as the resonant frequency of the building, the impulse to generate the vibration is small. Note that our calculation on the subject (FM 7.2 Exhibit 5) agrees with the document provided by American Hydro (FM 7.2 Exhibit 7);

2. There are strong photographic indications that the crack was present very early in the hydro-blasting process (FM 7.2 Exhibit 14);

3. The ability of the water jet to vibrate and push the liner plate slightly in the radial direction is compatible with its inability to put a thick section of concrete in vibration; An important caveat to add is that although the forces generated by the water jet are not sufficient to generate the delamination, it is possible they could have been instrumental in propagating it. Once the crack started in the plane of the tendon sleeves, it is "active" because it is in an area of local tensile stresses. Therefore it can be propagating with minimal forces serving as an "activation energy" force just pushing the local tensile stress above the tensile strength of the concrete.

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Conclusion:==

Vibration induced by hydro-blasting was not a factor in creating the delamination.

Itcould have been a factor in the propagation of the delamination.

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Ba not - - rh with Draft 1

FM 7.2 Exhibit 1 page 1 of 16 TECHNICAL GUIDELINES Prepared by the International Concrete Repair Institute September 2004 Guide for the Preparation of Concrete Surfaces for Repair Using Hydrodemolition Methods Guideline No. 03737 Copyright © 2004 International Concrete Repair Institute All rights reserved.

International Concrete Repair Institute 3166 S. River Road, Suite 132, Des Plaines, IL 60018 Phone: 847-827-0830 Fax: 847-827-0832 Web: www.icri.org E-mail: info@icri.org 925

926 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 2 of 16 About ICRI Guidelines The International Concrete Repair Institute (ICRI) literatureon concrete repair methods and materials was founded to improve the durability of concrete as they have been developed and refined Neverthe-repairandenhance its valuefor structureowners. The less, it has been difficult to find critically reviewed identification,development, andpromotionofthe most information on the state of the art condensed into promisingmethods andmaterialsis a primaryvehicle easy-to-useformats.

for accelerating advances in repair technology. To that end, ICRI guidelines are prepared by Working through a variety offorums, ICRI members sanctioned task groups and approved by the ICRI have the opportunity to address these issues and Technical Activities Committee. Each guideline to directly contribute to improving the practice of is designed to address a specific area of practice concrete repair recognized as essential to the achievement of A principal component of this effort is to make durable repairs. All ICRI guideline documents carefully selected information on important repair are subject to continual review by the membership subjects readilyaccessible to decision makers. During and may be revised as approved by the Technical the past several decades, much has been reported in Activities Committee.

Technical Activities Committee Producers of this Guideline Rick Edelson, Chair Subcommittee Members David Akers Pat Winkler, Chair Paul Carter Don Caple Bruce Collins Bruce Collins William "Bud" Earley Eric Edelson Garth Fallis Ken Lozen Tim Gillespie Bob Nittinger Fred Goodwin Steve Toms Scott Greenhaus Robert Johnson Kevin Michols Contributors Allen Roth Scott Greenhaus Joe Solomon Rick Toman Mike Woodward Synopsis Keywords This guideline is intended to provide an Bond, bonding surface, bruising, chipping introduction to hydrodemolition for concrete hammer, coating, concrete, delamination, removal and surface preparation, the benefits deterioration, full depth repair, hand lance, and limitations of using hydrodemolition, high-pressure water, hydrodemolition, impact and an understanding of other aspects to be removal, mechanical removal, micro-fracture, addressed when incorporating hydrodemolition post-tensioning, rebar, reinforced concrete, into a repair project. This guideline provides reinforcing steel, robot, rotomill, safety, sound a description of the equipment, applications, concrete, surface preparation, surface profile, safety procedures, and methods of water surface repair, tendon, vibration, wastewater, control and cleanup. and water jet.

This document is intended as a voluntary guideline for the owner, design professional, and concrete repair contractor. It is not intended to relieve the professional engineer or designer of any responsibility for the specification of concrete repair methods, materials, or practices. While we believe the information contained herein represents the proper means to achieve quality results, the International Concrete Repair Institute must disclaim any liability or responsibility to those who may choose to rely on all or any part of this guideline.

f

FM 7.2 EXAIRARATION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION METJJW 3 of 16 927 Purpose This guideline is intended to provide owners, Hydrodemolition has been used on the following types of structures:

" Bridge decks and substructures design professionals, contractors, and other " Parking structures interested parties with a detailed description of " Dams and spillways the hydrodemolition process; a list of the benefits " Water treatment facilities and limitations of using hydrodemolition for

• Tunnels and aqueducts concrete removal and surface preparation; and an " Nuclear power plants understanding of other aspects to be addressed " Piers and docks when incorporating hydrodemolition into a repair " Stadiums project. The guideline provides a description of

• Warehouses the equipment, applications, safety procedures, " Retaining walls and methods of water control and cleanup. This guideline is not intended as an operating manual for hydrodemolition equipment as that information The Effects of is specific to each equipment manufacturer.

The scope of this guideline includes the use of hydrodemolition for the removal of Mechanical deteriorated and sound concrete in preparation for a concrete surface repair. In addition, the use Impact Techniques Mechanical methods such as chipping hammers, of hydrodemolition for the removal of coatings rotomills, scabblers, and scarifiers remove concrete is discussed. by impacting the surface. These procedures crush While the procedures outlined herein have (bruise) the surface, fracture and split the coarse been found to work on many projects, the aggregate, and create micro-fractures in the requirements for each project will vary due to substrate (Fig. 1 and 2). As a result, the ability of many different factors. Each project should be the fractured substrate to provide a durable evaluated individually to ascertain the applica-bility and cost-effectiveness of the procedures described herein. Other methods of surface preparation are discussed in ICRI Technical Guideline No. 03732, "Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlays."

Introduction Hydrodemolition is a concrete removal technique which utilizes high-pressure water to remove deteriorated and sound concrete. This process provides an excellent bonding surface for repair material. First developed in Europe in the 1970s, Fig.1. Damage created by chippinghammer this technology has become widely accepted for concrete removal and surface preparation throughout Europe and North America.

Hydrodemolition can be used for horizontal, vertical, and overhead concrete removals and surface preparation on reinforced and non-reinforced structures. It is effective in removing concrete from around embedded metal elements such as reinforcing steel, expansion joints, anchorages, conduits, shear connectors, and shear studs. Hydrodemolition can be used for localized removals where deterioration is confined to small areas and for large area removals in preparation MIFucbjm for a bonded overlay. This technology can also be used to remove existing coatings from concrete. Fig.2: Damage created by rotomilling

928 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 4 of 16 bond with the repair material is compromised, requiring a second step of surface preparation to remove the damaged region.

Furthermore, impact methods may damage the reinforcing steel and embedded items such as conduit, shear studs and connectors, and expansion joint hardware. Impact methods transmit vibrations through the reinforcing steel, which may cause further cracking, delamination, and loss of bond between the reinforcing steel and the existing concrete. Vibration and noise created by the mechanical impact will travel through the structure, disturbing the occupants. During repair of thin Fig. 3: Surface preparedby hydrodemolitionhas a slabs and precast tees, chipping hammers may rough irregularprofile with protrudingaggregateand shatter the substrate resulting in unanticipated full is excellent for creatinga mechanical bond depth repairs.

For a discussion on surface bruising and the mechanical bond and composite action between mechanics of concrete removal by impact methods, the substrate and the repair material.

refer to ICRI Technical Guideline No. 03732, The rough, irregular surface profile provided "Selecting and Specifying Concrete Surface Preparation by hydrodemolition can result in bond strengths for Sealers, Coatings and Polymer Overlays." that equal or exceed the tensile strength of the existing concrete. The concrete surface profile Hydrodemolition can exceed CSP-9 (very rough) as defined in ICRI Technical Guideline No. 03732.

Benefits Rotomills and scarifiers remove concrete to a uniform depth and may leave deteriorated concrete below the specified depth. Alterna-and Limitations tively, the waterjet moves in a consistent pattern The benefits of hydrodemolition can be placed into over the surface and will remove unsound two groups: structural benefits that improve the concrete even if it is below the specified depth.

quality of the repair, and environmental benefits Since the waterjet does not create mechanical that improve the quality of the work place. impact, vibration is not transmitted into the structure Hydrodemolition also has limitations, which need from the hydrodemolition operation. Delami-to be considered. nation beyond the repair area caused by vibration of the reinforcing steel is greatly reduced.

Structural Benefits During hydrodemolition, sand and cement

" A rough, irregular surface profile is created particles mix with the waterjet. The abrasive action to provide an excellent mechanical bond for of theses particles is usually sufficient to clean repair materials; uncoated reinforcing bar and embedded metal

" Surface micro-fractwring (bruising) is eliminated; items without damaging them. Corrosion material

" Exposed aggregates are not fractured or split; is removed from the reinforcing bar and metal

• Lower strength and deteriorated concrete is items, allowing for easy inspection and identifi-selectively removed; cation of cross-sectional area loss. The reinforcing

" Vibration is minimal; bar is cleaned without any loss of deformations.

" Reinforcement is cleaned, eliminating the need Cleaning of the entire reinforcing bar, however, for a second step of surface preparation; and will not occur if the reinforcing bar has not been

• Reinforcing and other embedded metal elements completely exposed during hydrodemolition.

are undamaged.

During concrete removal, the waterjet is directed Environmental Benefits at the surface, causing high-speed erosion of the " Minimizes disruptions to users of occupied cement, sand, and aggregate. The water jet does space by significantly reducing transmitted not cut normal weight aggregate which remains sound through the structure; intact and embedded as part of the rough, irregular

• Increased speed of concrete removal can surface profile (Fig. 3). The aggregate interlocks reduce construction time; with the repair material to assist in developing a " Minimizes dust; and

FM 7.2 ExRIOM!A1*,TION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION MET"90 5 of 16 929

• Robotic units reduce labor and minimize " The water jet will remove the sheathing from injuries as compared to chipping hammers. post-tensioning tendons and may drive water Concrete removal by hydrodemolition can take into the tendon; place inside an occupied structure, such as a hotel, " The hydrodemolition robot may be too large to apartment building, office building or hospital access small or confined areas of the structure; with minimal noise disruption to the occupants. " The waterjet can damage coatings on reinforcing Hydrodemolition can quickly remove concrete. steel and other embedded items; As such, project duration can be reduced, mini- " The waterjet can introduce water into electrical mizing the impact on the users of the structure. system components, especially if embedded During demolition, cleanup, and final wash in the concrete and already deteriorated or not down, the concrete debris and repair surface remain properly sealed; and wet, minimizing dust in the work area. Since hydro-

• If cleanup is not properly performed in a demolition cleans the reinforcing steel, the need timely manner, further surface preparation to sandblast is eliminated unless additional concrete may be required.

removal is required using chipping hammers. As such, silica dust in the work area is reduced, thereby providing a safer work environment. The Hydrodemolition The use of chipping hammers and other impact methods are labor intensive and physically demanding, which can cause injury to the employee.

System The hydrodemolition system consists of a Robotic hydrodemolition equipment reduces the support trailer or vehicle, high-pressure use of these tools and the possibility of injury. pump(s), a robotic unit to perform the demolition, and high-pressure hoses to connect the pump(s)

Limitations to the robot. Hand lances are also available

" The hydrodemolition process consumes a to remove concrete in areas inaccessible to significant amount of water (6 to 100 gpm the robot.

[25 to 380 1pm]). A potable water source must be available. The cost of the water should Support Trailer be considered; Hydrodemolition units are typically transported

" Wastewater containing sand and cement fines on 40 to 50 ft trailers (Fig. 4). The robot may (slurry) must be collected, treated, and returned to the environment. Wastewater disposal may require a permit;

• Projects requiring total demolition can be done faster and more economically with crushers and similar equipment;

" Water can leak through cracks in the concrete and damage occupied space below the repair area. Hydrodemolition should not be used over occupied areas due to the risk of blow-through (unanticipated full-depth removal);

" Repair areas of varying strength will result in non-uniform removal. Areas of high strength may need to be removed using hand lances or Fig. 4: Hydrodemolitionsupport trailerA self-chipping hammers; containedunit transportspumps, robot,hoses,

" The water jet is blocked by reinforcing steel and spareparts resulting in concrete shadows under the reinforcing bar that may need to be removed be transported on the same trailer or separately using hand lances or chipping hammers; on a smaller trailer. The support trailer usually

• Since the waterjet of a robotic unit is contained contains a supply of spare parts, tools, maintenance in a metal shroud, some robots are unable to area, fuel and water storage, supply water completely remove concrete up to a vertical hoses, and filters. These units are designed surface such as a curb, wall or column. The to be self-sufficient on the job site with adequate remaining concrete may have to be removed spare parts to perform routine maintenance using hand lances or chipping hammers; and repairs.

930 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 6 of 16 High Pressure Pumps The high-pressure pumps used for hydrodemolition are capable of generating pressures from 10,000 psi to 40,000 psi (70 to 275 MPa) with flow rates from 6 to 100 gpm (25 to 380 lpm).

The pumps are driven by a diesel or electric motor, typically operating between 100 and 700 horsepower. The engine size will vary based on the flow and pressure rating of the pump. The pumps operate most efficiently at their design pressure and flow. High-pressure hoses connect the pumps to the robot. The pumps may be located a significant distance (500 ft [150 m])

Fig. 6: Nozzle is mounted on a traversebeam from the actual removal area. However, due to a drop in pressure and flow through the high-pressure hoses, the pumps should be located as close as possible to the removal area, typically within 300 ft (100 m).

Robotic Removal Unit- Rotation Oscillation Horizontal Surfaces The force created by the high-pressure pump(s) is controlled using a robotic removal unit (Fig. 5).

The robot is a diesel or electric powered, self-propelled, wheeled or tracked vehicle. It is used to uniformly move and advance the waterjet over Fig. 7: Rotating or oscillatingnozzles the surface during concrete removal.

rig.c: lotanngnozzies are angiea mrom center Fig.5: Typical hydrodemolitionrobot The water jet is mounted on a trolley that traverses over the removal area along a cross feed An9W Nmk or traverse beam (Fig. 6) perpendicular to the advance of the robot. The water-jet nozzle may 13.000 41JMw0ow Wrnim-Komaly either oscillate or rotate (Fig. 7). The oscillating %p0id WWL*

nozzle is angled forward in the direction of the traverse. Rotating nozzles are angled from the center, creating a cone effect while rotating (Fig. 8 and 9).

The nozzle assembly is enclosed within a steel shroud with rubber seals around the perimeter to contain the debris during demolition (Fig. 10). Fig.9: Rotation of the anglednozzle createsa water cone

FM 7.2 ExRI!A1MATION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION MEfRPP 7 of 16 931 3 seconds and the waterjet may traverse only one time before the robot advances 2 to 4 in. (50 to 100 mm).

The depth of concrete removal is controlled at the robot. Since the pumps are designed to operate at a specific pressure and flow rate, it is unusual to reduce the pressure (and subsequently the flow rate) to adjust the depth of removal.

Narrow areas may be removed by adjusting sensors that limit the movement of the water jet along the traverse beam. The traverse and advance functions limit the removal to a rectangular area along the advance path of the robot. Because the Fig.10: Nozzle is enclosed within a steel shroud water jet is contained within a steel shroud, most robots are unable to remove concrete within 3 to The rotation/oscillation of the nozzle combined 6 in. (75 to 150 mm) of vertical surfaces.

with the traverse and advance of the robot provide a uniform and continuous motion of the water jet over the removal area (Fig. 11). Each of Specialized Robotic Equipment-these functions is fully adjustable. The depth of Vertical and Overhead Surfaces concrete removal is determined by the length of Various types of robotic equipment are available time the waterjet is directed at the removal area. to perform removals on walls, soffits, substructures, beams, columns, and tunnels. These robots are often built on wheeled or tracked vehicles and have the ability to lift the traverse beam into the vertical or overhead position. The primary functions of traverse and advance are utilized in order to provide uniform concrete removal during vertical and overhead repairs.

As an alternative to the robot, the waterjet may also be attached to a frame that allows the jet to move in a two dimensional "X-Y" plane. The X-Y movement of traverse and advance are present in these units to provide uniform concrete removal.

The X-Y frames can be lifted and positioned over Fig. 11. The waterjet traverses back and forth perpen- the removal area using a crane, backhoe, all-dicularto the forward advance of the robot terrain forklift or other similar equipment.

Adjusting the following parameters will increase Hand Lance or decrease the depth of removal: Hand lances operate at pressures of 10,000 to

a. Total traverse time (time of each traverse x 40,000 psi (70 to 275 MPa) while delivering number of traverses); and approximately 2 to 12 gpm (8 to 45 1pm) of water.

b. Distance of the advance. Hand lances are not as fast or as precise for Once these parameters are set, the robot will concrete removal as a programmed robot and are reproduce the settings in a programmed sequence slower than chipping hammers. Hand lances are to provide consistent removal of the concrete. For effective in performing light scarification and example, during deep removal to expose the coating removals. It should be noted that the reinforcing bar 3 to 4 in. (75 to 100 mm), the water jets on hand lances may not be shrouded, traverse speed may be 8 seconds (the time increasing the risk of debris becoming airborne.

required for the waterjet to move from one side of Hand lances can be used for removal of:

the traverse beam to the other) and the water jet

• Concrete shadows below reinforcing bar; may traverse 3 times before the robot advances

• Concrete adjacent to walls, columns, curbs, forward I to 2 in. (25 to 50 mm). On the other hand, and in tight and confined areas not accessible for light scarification 1/4 to 1/2 in. (6 to 13 mm) to the robotic equipment; and or coating removal, the traverse speed may be

• Coatings.

932 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 8 of 16 Safety Hydrodemolition involves the use of potentially dangerous specialized equipment. At all times, the manufacturer's instructions for the safe operation of the equipment and personal protective equipment should be followed, as well as all local, state, and federal regulations. Hydrodemolition units should be supervised and operated by qualified personnel certified by the equipment manufacturer.

Hydrodemolition employs high-velocity water jets to demolish concrete and perform surface preparation. Even though the waterjet is shrouded ig. 12: Scarifiedsurfacewith I in. aggregate on robotic units, debris can be propelled from beneath the shroud with sufficient velocity to cause serious injury. Serious injury or death can also occur if struck by the waterjet. Hand lances are typically not shrouded and care must be exercised to avoid injury when using these tools.

Workers, equipment operators, and any indi-viduals entering the work area are required to wear hard hats, safety glasses, hearing protection, safety shoes, gloves, long pants and long-sleeve shirts, and must be trained in the proper use of personal protective equipment. When using a hand lance, the operator should wear a full-face shield, rain suit, and metatarsal and shin guards.

Additional protective clothing may also be required Fig. 13: Scarifiedsurface with 3/4 in. aggregate for use with hand lances. Everyone involved with the hydrodemolition operation should receive a concrete overlay. If the surface was previously specific training outlining the dangers associated rotomilled, the minimum removal depth using with the use of high-pressure water. hydrodemolition should equal the size of the Prior to starting demolition, an inspection of coarse aggregate to remove all concrete micro the area should be performed including the area fractures and damaged or crushed aggregate.

under the work area. All barricades, partitions, Scarification may not remove all unsound shielding, and shoring must be installed and concrete due to the rapid rate at which the water jet warning signs posted to prevent unauthorized moves over the surface. It may be necessary to entry into the work area. The area below the work resurvey the scarified surface and identify delami-area must be closed off and clearly marked nated or deteriorated areas for further removal.

"Danger- Do Not Enter." Electrical conduits or other electrical equipment in the work area should Partial Depth Removal be deenergized to avoid electrical shock. Partial depth removal is commonly required if Special precautions are required for post- chloride contamination has reached the top mat tensioned structures as referred to in the section of reinforcing steel or deterioration, delamination "Considerations for Hydrodemolition Use." or spalling occurs within the top mat of reinforcing steel. Partial depth concrete removal can expose Hydrodemolition the top mat of reinforcing steel and provide clearance, typically a minimum of 3/4 in. (19 mm),

Applications below the bottom reinforcing bar of the top mat (Fig. 14 and 15). Determining the reinforcing bar size and concrete cover are critical to determine Scarification the required removal depth.

Scarification is performed to remove the surface Concrete removal using hand lances or chipping concrete and provide a rough profile (Fig. 12 and hammers may be required to remove shadows 13). Scarification is often used in preparation for under the reinforcing bar, previously repaired areas

FM 7.2 ExlfRilMATION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION MET$Wu 9 of 16 933 used. Other structural elements such as shear connectors, shear studs, and steel beam flanges can be exposed without damage.

During full depth removal, the removal rate slows as the depth increases because the water jet stream dissipates as it moves away from the nozzle and the water jet must push more water and debris from its path prior to contacting the surface to be removed.

Full depth removal is often necessary on waffle or pan joist slab systems (Fig. 16).

Fig. 16: Full depth removal-waffle slab

g. 15. Partialdepth removal on a retainingwall Coating Removal or high areas resulting from variations in the Hydrodemolition can be used for the removal strength of the concrete. In addition, concrete of epoxy, urethane, hot applied membrane, and removal may be necessary adjacent to vertical other coatings from concrete surfaces (Fig. 17).

surfaces such as curbs, walls and columns. Saw When performing coating removal, a multiple cutting of the perimeter of the repair area, if jet nozzle is used. The multiple jets allow the required, should be performed after hydro- water to penetrate the coating without damaging demolition to prevent damage to the saw cut. This the concrete. However, if the concrete below the will require additional concrete removal along coating is deteriorated, it may be removed along the repair perimeter with hand lances or chipping with the coating.

hammers. If the saw cut is made first, the area outside the saw cut should be protected using a steel plate. The steel plate will allow the waterjet to slightly over run the saw cut without damaging the surface outside the saw cut while completely removing the concrete within the repair area.

Full Depth Removal Hydrodemolition can be used for full depth removal where delamination has occurred in the lower mat of reinforcing or chloride contami-nation exists throughout the entire thickness of the slab. Full depth removal can be performed along expansion joints and other areas where there is a high concentration of reinforcing steel that may Fig. 17: Coating removal using a spinning,multi-nozzle be damaged if conventional removal methods are spray head

934 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 10 of 16 If the strength of the concrete increases or The Hydrodemolition a high-strength repair area is encountered during hydrodemolition, the removal depth will Process decrease (Fig. 19). The decrease in depth may not be immediately detected by the operator, resulting Concrete removal by hydrodemolition is impacted by the following factors: in an area of shallow removal (Fig. 20). To obtain

" Size and density of the aggregate; the required depth in higher strength concrete,

" Concrete strength; the total traverse time is increased and the

• Uniformity of concrete strength; advance of the robot is decreased. If the high-

• Extent of cracking; strength repair area is large enough, it may be

" Deterioration and delamination; possible to set up the hydrodemolition robot over

" Surface hardeners; the area and remove to the specified depth. This

" Previous repairs with dissimilar strength material; and

" Size and spacing of reinforcing steel or other embedded items.

In sound concrete, the variation in the depth OWNcjoCro.

6.W000A=UOPo.' I1 I of removal will generally equal the size of the Non0 ~kCo*cmto-54IAt, W ps0i coarse aggregate (Fig. 18). For example, if the coarse aggregate is 1 in. (25 mm), D = 1 in. 1 (25 mm) and the specified depth of removal is 2 in. (50 mm), the range of removal will be 2 in.

(50mm) +/- D/2 (1/2 in. or 13 mm), or 1-1/2 in.

(38 mm) to 2-1/2 in. (63 mm).

I Fig. 18: The depth of removal depends on the size of the course aggregate During hydrodemolition, a high-pressure water jet is uniformly moved over the surface and, provided the concrete is sound and the strength does not change significantly, the removal depth will remain consistent. Depth variations occur when the concrete strength changes, cracking or delamination is present, the concrete is deteriorated or the surface has been previously repaired using a different type and strength of material. In comparison, rotomilling or dry-milling equipment can be set to a specific depth and the milling drum will mill the surface Fig. 19: High-strength concrete is removed at a slower to that depth regardless of any variations in the rate than normal concrete, which can result in a non-concrete strength, quality or level of deterioration. uniform removal

FM 7.2 ExI I{A1AMATION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION MOUP1 1 of 16 935 Fig.20: High-strengthrepairarea within the hydro-demolition area procedure can be problematic for two reasons.

First, if the water jet overruns the high-strength repair area, it may result in a blow-through or full depth removal at the perimeter of the high-strength repair area. Second, since the water jet must be slowed significantly, it may cause excessive removal below the high-strength area once it is removed and the softer base concrete is exposed.

For these reasons, it is often preferable to use chipping hammers in high-strength repair areas.

The opposite effect is encountered if the concrete strength decreases or there is cracking, deterioration or delaminations (Fig. 21). Concrete that is deteriorated, low strength or delaminated is removed faster than the surrounding sound concrete by the water jet. For example, if the average removal depth is 2 in. (50 mm) and there is a delamination that is 2 in. (50 mm) deep, the actual removal within the delaminated area could be 3 to 4 in. (75 to 100 mm) deep. For this reason, removal in an area that is seriously deteriorated and delaminated may not be consistent.

This effect is often described as "selective removal of deteriorated concrete." While the water Fig.21: Delaminatedor deterioratedconcrete is jet is traversing and advancing uniformly over removed at a fasterrate leading to non-uniform removal the surface, it is removing unsound, delaminated, deteriorated, cracked, and low strength concrete is most difficult at reinforcing bar intersections.

selectively below the specified removal depth. Increasing the specified depth of removal will Selective removal is not without limitations. minimize the amount of shadowing.

For example, if the robot is traversing and advancing Pointing the water jet under the reinforcing rapidly as during scarification, it may not remove bar can reduce concrete shadows. This can be deeper delaminations. accomplished by using a rotating or oscillating Size and spacing of the reinforcing steel will nozzle (refer to Fig. 7-9). Rotating nozzles are also influence the removal depth. The reinforcing typically angled 10' and 300 from center. The steel blocks the waterjet and shields the concrete nozzle rotates between 100 and 1800 rpm, creating below, creating concrete "shadows" (Fig. 22 and a demolition cone that will undercut both the 23). Removal of concrete shadows becomes more transverse and parallel reinforcing bar provided difficult as the reinforcing bar size increases and the specified removal depth is greater than the

936 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 12 of 16 Fig.23: "Shadow" under the rebar(note tie wire undamagedandin excellent condition) removal may result in the removal of sound concrete, it will minimize the need for concrete removal under the reinforcing bar with chipping hammers or hand lances.

Considerations for Hydrodemolition Use Issues that should be considered when evalu-ating the use of hydrodemolition for a repair project include:

Limited quantity of repair:Mobilization and set up of the hydrodemolition equipment can be expensive. If there are only minor repairs or a limited quantity of repairs, the mobilization cost may make the process uneconomical.

Increasein repairquantity: The traverse and advance function of the hydrodemolition robot results in removal areas that are rectangular. The removal areas may have to be "squared up" in order for the hydrodemolition equipment to efficiently remove the concrete. "Squaring up" the repair areas may lead to an increase in the Pig. ZZ: Keintorcingsteel blocks the waterjet leaving a removal quantity and the cost of the project.

concrete "shadow" under the reinforcing.Increasingthe Reinforcing bar size and concrete cover:

removal depth will decrease the amount of shadowing Partial-depth removal normally requires clearance below the bottom reinforcing bar of the top mat depth of the reinforcing bar. Similarly, the oscil- of reinforcing. The size and quantity of the lating nozzle moves from side to side as it traverses, reinforcing bar and the concrete cover over the directing the water jet at an angle to the surface, reinforcing bar should be determined in order to cutting under the reinforcing bar. The nozzle is specify the correct removal depth to achieve the angled forward as it traverses left, and at the end required clearance.

of the traverse, flips to face forward as it traverses Potentialforfull-depth blow-throughs:Hydro-right. To minimize concrete shadows, the required demolition of severely deteriorated structures depth of removal should be at least 3/4 in. (19 mm) may result in full-depth blow-throughs. Blow-below a #5 reinforcing bar. Larger reinforcing throughs may take place where full depth slab bars will require a greater removal depth to cracks occur, especially if deterioration is evident minimize shadowing. While this additional on the slab underside. Shielding may be required

FM 7.2 ExMINARAATION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION MOJJJi 3 of 16 937 to protect the area below from damage. Shoring of the structure. Temporary shoring may be below the blow-through may be damaged or needed to move the pumps into the structure.

destroyed. When the water jet is in the open air, Available water sources: Pumps used for as will happen when the waterjet blows through hydrodemolition require a steady supply of clean the deck, it is extremely noisy (may exceed water at a sufficient volume to perform the work.

130 db) and dangerous. Sound resistant partitions Generally, local municipal water is used for should be installed to contain the noise within the hydrodemolition. Sources close to the work area, structure if blow-throughs are expected. such as a nearby fire hydrant or water line feeding Extent of previous repairs: Repair materials the structure, should be adequate. Specific water may have a different compressive strength than requirements will vary, depending on the hydro-the original concrete. Since the hydrodemolition demolition unit used for the project and the jet is set to move at a uniform rate, the presence method of cleanup. Cleanup performed using a of dissimilar strengths of material will result in a fire hose operating at 100 to 200 gpm (380 lpm variation in the depth of removal. Higher strength to 760 lpm) will use substantially more water areas may require further concrete removals using than an 8000 to 10,000-psi (55 to 70 MPa) water chipping hammers or hand lances to achieve the blaster operating at 8 to 12 gpm (30 to 45 1pm).

specified depth of removal. Lower strength areas In remote areas, water can be drawn from wells, may result in deeper removals and possibly full- fresh water lakes, rivers, or streams. This water depth blow-throughs. must be pre-filtered to remove any suspended Occupiedareasadjacentto or under the repair solids to avoid damage to the high-pressure area:Occupied spaces such as stores or offices pumps. Recycled water has been used for hydro-may occur in the structure. It may not be practical demolition, however, it can add substantially to perform hydrodemolition adjacent to or over to the cost of the project due to collection and these areas. Water from the hydrodemolition may filtration of the water and the added wear to leak to the occupied level below. As such, the the equipment caused by dissolved minerals in repair area should be protected to prevent water the recycled water. When available, potable from entering the occupied area. water is used. Water may have to be trucked into Shoring requirements: During structural remote locations.

repairs, concrete may be removed from around Post-tensionedstructures: The use of hydro-the top reinforcing. An analysis of the structural demolition on post-tensioned structures has capacity of the remaining slab section should be potentially severe risks and must be carefully made by a qualified engineer to determine if evaluated to maintain a safe working environment, shoring will be required. The weight of the maintain structural integrity, and to preserve the hydrodemolition robot should be considered long-term durability of the structure. Sudden when determining shoring requirements. release of anchorages can result in dangerous Equipment location: The hydrodemolition explosive energy and flying debris capable of equipment is transported on a trailer. If possible, causing damage to equipment and serious injury the pumps should be located within 300 ft of or death to workers. Tendons should be de-tensioned the repair area. A suitable location next to the prior to removing concrete from around anchorages structure must be selected. Pump units that are to prevent the sudden release of the anchorages powered by diesels engines should not be located and loss of pre-stress forces. The loss of pre-stress next to the air intake of adjacent buildings. In forces may result in the loss of structural integrity congested metropolitan areas, the pumps may be and result in the need for shoring. Careful eval-removed from the trailer and placed within the uation must also be exercised when removing structure. Diesel powered pumps will need to be concrete around post-tensioning tendons. Removal located close to an exhaust shaft and the exhaust of concrete around tendons can result in a change from the pumps piped to this location. A fuel tank of tendon profile, which may also result in the will also have to be placed in the pump area and loss of prestressing force and structural integrity.

provisions made to fill the tank as required. The wires or strands of post-tensioning tendons Although electric pumps may be used inside the are usually undamaged during hydrodemolition, structure eliminating the fueling and exhaust however the sheathing and protective grease will concerns, they have a substantial power requirement be removed from unbonded tendons. In bonded and will need an electrical service installed. Due post-tensioning tendons, the waterjet may penetrate to the weight of the pumps, they may need to be the duct and remove the grout inside. In either placed on the slab on ground or in a shored area case, the hydrodemolition water may enter the

938 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 14 of 16 tendon at the edge of the repair area and can be and stored and temporary lighting installed.

driven into the tendon outside the work area. Sprinkler heads may need to be protected. Mist and Water remaining in the tendon can cause future high humidity in the Work area could damage corrosion affecting the long-term durability of the electrical panels and other services. Items remaining post-tensioning system. Each tendon must be in the work area should be protected.

carefully examined and any water that has entered Temperature: When the temperature falls the tendon removed. Both the grease and the below freezing, the structure must be heated or protective sheathing must be restored. the hydrodemolition stopped to prevent water It may not be possible to remove moisture that from freezing in the work area.

has entered the post-tensioning system during the hydrodemolition process. In addition, verification of the presence of moisture is difficult and Test Area ,

may not be possible. Refer to ICRI Technical A test area should be designated to establish the Guideline No. 03736, "Guide for the Evaluation operating parameters and to demonstrate that the of Unbonded Post-Tensioned Concrete Structures," equipment, personnel, and methods of operation for suggested procedures to detect water in post- are capable of producing satisfactory concrete tensioning tendons. Long term monitoring for removal results. The test should include sound future corrosion may also be prudent. and deteriorated concrete areas, each a minimum Conduitand embedded metal items: Embedded of 50 ft2 (5 m2). First the robot is set to remove aluminum and steel conduit will not be damaged sound concrete to the specified depth. Once the by hydrodemolition if they are in good condition. operating parameters have been determined, However, deteriorated portions of aluminum and the equipment is moved to the deteriorated area steel conduit will be damaged and water will and a second test is performed using the same enter the conduit system. PVC conduit will be operating parameters. If satisfactory results are damaged during hydrodemolition. As a safety achieved, the quality and depth of removal precaution, all conduits should be deenergized will become the standard for the project. If hand during demolition. Other metal items within lances are to be used to perform concrete the removal area such as shear connectors, shear removals, they should also be demonstrated to studs, and anchorages will not be damaged show satisfactory results.

by hydrodemolition. It is noted that the hydrodemolition robot will Noise limitations:Hydrodemolition does not move the water jet over the surface in a constant produce sound that is transmitted through a motion and if the concrete is of uniform strength, structure, however, the noise from the hydro- the removal depth will be consistent. However, demolition unit in the work area is sufficiently since concrete is seldom uniform, there will be loud to be objectionable to the public. Further- variations in the removal depth on the project.

more, noise can be excessive during full-depth Other factors affecting the removal depth include repairs or blow-throughs. Sound reducing partition the extent and depth of deterioration, the size and walls that separate the public from the work area quantity of reinforcing bar, the concrete cover may be required. Acoustical studies indicate that over the reinforcing bar, and the presence of the sound waves created by hydrodemolition are surface hardeners. As the equipment is used, low frequency and are best controlled using dense nozzles will wear, changing the force created material such as sheet rock or concrete board. by the water jet. As such, the hydrodemolition There are a variety of sound deadening materials equipment operator must monitor the depth and supplied by various vendors that have proven quality of removal and adjust the parameters of effective in controlling noise. Partition walls the robot to provide consistent removal through-should be protected from moisture. If properly out the project.

sealed at the base, a water resistant sound reducing partition wall will also assist in containing the water within the work area. Wastewater Control Protection of lighting, sprinklers, and other Controlling the wastewater has often been viewed services. Light fixtures, fire protection systems, as one of the more difficult tasks associated with and other services may be damaged by airborne the use of hydrodemolition. However, with pre-debris from the hydrodemolition or clean up planning and proper installation of a wastewater operation. If full depth removal or blow-throughs control system, the water can be properly managed are anticipated, light fixtures may need to be removed (Fig. 24). Hydrodemolition wastewater should be

FM 7.2 ExAffltilA1*,TION OF CONCRETE SURFACES FOR REPAIR USING HYDRODEMOLITION M*T"J3 5 of 16 939 Water containment and collection systems will vary depending on the structure. Where possible, it is best to take advantage of gravity to move the water to the treatment area. In many structures, the slab on ground can be used to collect and treat the water. The water may be allowed to flow through the structure to the lowest level or through the existing drains, which have been disconnected just below the underside of the first supported level. All slab-on-ground drains should be plugged and water should not be allowed to enter the drainage system prior to treatment. Once the water is clear and the pH adjusted, it can be Fig. 24: Typical wastewater handlingsystem pumped directly to the discharge point. Additional treatment capacity may be necessary if rainwater discharged to the storm or sanitary sewer or to cannot be separated from the wastewater.

the ground for absorption and/or evaporation Floor slabs and decks are commonly crowned under permit from the controlling authority. or sloped to provide drainage. Since water will Discharge into an existing storm or sanitary line run to the low area, a simple method of water may occur in the structure or to a nearby storm control involves the use of hay bales or aggregate or sanitary line accessed through a manhole. A dams, which can be set up along curb lines or the 4-in. (100 mm) connection should be adequate. perimeter of the work area. As the water ponds Wastewater may not be discharged directly to a in front of the hay bales or aggregate dams, the wetland, stream, river or lake. suspended solids will settle out. In areas where Hydrodemolition wastewater contains suspended the drains are plugged, the water is forced to pass particles and typically has a pH of 11 to 12.5. The through the hay bales or aggregate dams. Retention wastewater is initially placed in settling tanks ponds can be built at the end of the structure and or ponds to reduce the suspended solids. The the water directed or pumped to these ponds.

particles are heavy and settle out quickly as Settling tanks can also be used and the water the water is allowed to stand. This can also be pumped from the structure to the tanks.

accomplished by allowing the water to pass through a series of berms that are lined with filter fabric or hay bales. Debris Cleanup The controlling authorities for discharge have varying requirements for the level of suspended and Disposal solids and the range of pH for discharge into their Hydrodemolition debris consists of wet sand, system. Typically the water should be clear and aggregate, chips or chunks of concrete, and slurry the pH range between 5 and 10. Ponding the water. Slurry contains cement particles and ranges water will clarify it, however, the pH of the from muddy water to a thick paste. Removal of the wastewater may have to be reduced prior to debris should occur as soon as possible to prevent discharge. This can be accomplished by the the debris from solidifying and adhering to the introduction of acid, CO2 or other pH reducing surface, making cleanup more difficult.

materials into the wastewater. Adding flocculants Tools used for cleanup include: fire hoses, can assist in reducing suspended solids. A location pressure washers, compressed air, sweepers, skid for settling ponds or tanks and pH reducing steer loaders, vacuum trucks, and manual labor.

equipment should be determined. The types of cleanup will vary based on the The cost to discharge wastewater ranges from type of removal performed as follows:

the cost of a discharge permit to charges for the 1. Above the reinforcingbar-anyremoval depth actual water consumed and discharged. The cost above the top reinforcing bar of the top mat of of water consumed is generally that of commercial reinforcing and the reinforcing bar remains water usage within the community. The controlling supported by the concrete; authority may require monitoring and testing of 2. Below the reinforcingbar-anyremoval depth the wastewater. Local ordinance requirements must below the top mat of reinforcing bar in be reviewed and met prior to discharge, including which the top reinforcing bar mat becomes the obtaining of proper permits. unsupported by the original concrete; and

940 FM 7.2 Exhibit 1 CONCRETE REPAIR MANUAL page 16 of 16

3. Full-depthremoval.

During above the reinforcing bar clean up, equipment such as skid steer loaders, sweepers, and vacuum trucks may be driven over the surface to assist with the cleanup (providing they meet the weight requirements of the structure). The debris can be swept, pressure washed or air blown 3~4I., BckýRcbw into piles where it is picked up by a loader. A ?Amawu vacuum truck may be used to vacuum the debris from the surface. In all cases, the surface must Maw aw" be pressure washed to remove any remaining cement slurry.

If the removal is below the reinforcingbarand the reinforcing bar is unsupported, it is difficult Fig.: 25.: Measuringdepth of removal using a and possibly unsafe to drive equipment into the straightedge removal area. The debris can be removed by washing with a fire hose (large water consumption), The most common practice of measuring the pressure washing or blowing it onto the adjacent depth of removal is to place a straightedge on top original surface where it can be picked up with a of the original surface and extend it over the loader. A pressure washer operating at 8000 to removal area. Measurements are taken from the 10,000 psi (55 to 70 MPa) and 8 to 12 gpm bottom of the straightedge to determine the depth (30 to 451pm) is effective. Vacuuming has proven of removal. This quick and simple technique can very effective in removing debris from around only be used during the removal process and is the reinforcing steel, however, the surface will not applicable for final measurements in large require pressure washing to remove the cement removal areas.

slurry and paste. A string line may be pulled over the removal During full-depth removal, the debris simply area and measurements taken below the string.

falls to the floor below where it can be picked up However, this method could provide incorrect with a loader. results if slopes or crowns occur in the original The debris, which consists of wet sand, surface. Surveying equipment may be used and aggregate, chips or chunks of concrete, and is very accurate; however, to account for slopes, slurry is placed in dumpsters or hauled away in pitches and crowns in the original surface, a detailed trucks and may be recycled or placed in a landfill survey must be made of the original surface in accordance with the requirements of the prior to removal and measurements taken at the controlling authority. same locations after removal for comparison and determination of the actual removal depth.

Removal Depth Measurements Summary Effective concrete removal and proper surface Following hydrodemolition, the surface profile preparation are key elements to a successful repair is very rough and three depth measurements are project. A surface prepared using hydrodemolition possible (Fig. 25): is rough, irregular, and is excellent in creating a

1. Minimum removal-original surface to the mechanical bond with the repair material.

shallowest removal point. Hydrodemolition eliminates micro-fractures and

2. Maximum removal-original surface to the damage to reinforcing steel, minimizes transmitted deepest removal point. noise and dust, and cleans the reinforcing steel.

3. Average depth of removal-The difference The use of hydrodemolition may not be appro-between the minimum and maximum removal priate for every structure and a careful review of at the same location. the benefits and limitations of the process relative Measuring the depth of removal can be to each structure should be undertaken. Proper accomplished using: safety procedures must be observed at all times

1. A straight-edge placed on the original surface; when using hydrodemolition.

2. A string-line pulled over the removal area; and

3. A surveyor's level.

PC"MEý'2 Exhibit 2 ENGINEERING CHANGE pageOgOO6? 6 RO MAC & MAC HYDRODEMOLITION SERVICES INC.

Suite D-13, 301 West Holly Street, Bellingham, WA 98225 Tel: 1 800 665.7772

• Fax: 1 800 661.1178 Email: info@macandmac.com State of Washington Contractor License #MACMAHS996NB State of California Contractor License #80 PROGRESS ENERGY SERVICE COMPANY, LLC CRYSTAL RIVER THREE (CR3) NUCLEAR PLANT CRYSTAL RIVER, FLORIDA HYDRODEMOLITION WORK PLAN PROJECT Create a temporary opening in the CTMT wall removing all concrete using high pressure Hydrodemolition technology.

HYDRODEMOLITION EQUIPMENT 2 - 2000HP diesel pumping unit power packs. Each power pack contains 3 high pressure pumping units delivering 50 gpm @ 20,000 psi per pump to a Hydrodemolition7]

nozzle mounted on the Hydrodemolition concrete removal track.

HYDRODEMOLITION CONCRETE REMOVAL TRACK Stationed on access platform at temporary opening location. Track frame mounted on CTMT wall exterior outline of concrete to be removed 28' wide x 24' high.

Frame has two Hydrodemolition concrete manipulators mounted side by side, each covering 14' wide x 24' high Each manipulator contains three Hydrodemolition nozzles. Each nozzle is connected to a high pressure pump in the power pack.

HYDRODEMOLITION PROCESS Each manipulator passes over the surface removing concrete as it travels width wise one pass then index up 2 inches repeating the process until it reaches the top of the track (24' level). To prevent over cutting steel stops are installed at the 24' level.

When rebar is exposed manipulator is locked in place above the top (24') level while crews remove the rebar below. (Approx. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />)

When rebar is removed Hydrodemolition resumes until Tendons are exposed. When tendons are exposed manipulators are locked in place above the top (24') level while crews remove and plug the tendons below. (Approx. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />)

ATTACHMENT Z24R0 Page 3 of 7

PC"Eff .C2 Exhibit 2 ENGINEERING CHANGE page06006R0 MAC & MAC HYDRODEMOLITION SERVICES INC.

Suite D-13, 301 West Holly Street, Bellingham, WA 98225 Tel: 1 800 665.7772

• Fax: 1 800 661.1178 Email: info@macandmac.com State of Washington Contractor License #MACMAHS996NB State of California Contractor License #800844 When tendons are removed Hydrodemolition resumes until Liner plate is completely exposed.

When Liner plate is completely exposed Manipulators are locked in place until clear access is available to dismantle Frame.

RUBBLE CONTROL As Hydrodemolition is in progress the water and concrete rubble will fall down to the platform into a chute running down to rubble and wastewater containers located on the ground.

To prevent rubble from escaping the immediate area a screen hoarding will be erected around the Hydrodemolition track.

HYDRODEMOLITION EQUIPMENT STAGING 2 active Hydrodemolition power packs to be setup approx. 400' from reactor opening location.

Three hoses will run from each power pack to the Hydrodemolition Track. =

2 - power packs = 6 hoses supplying two 3 nozzle manipulators mounted on the Hydrodemolition track.

1 backup power pack ready to operate less high pressure hoses will be staged also.

WATER CONTROL Wastewater will be pumped from bins at the CTMT to wastewater treatment location in the staging area approx.400' away.

Discharged waste water will be:

• 6.0-9.0 PH

• Total suspended solids, 30ppm

" Oil in water, daily maximum of 18.4 ppm with a monthly average below 13.8 ppm

• List of all fluids, lubricants will be submitted for approval ACTIVITIES ATTACHMENT Z24R0 Page 4 of 7

6 Pft Exhibit 2 ENGINEERING CHANGE pageOOSOc? RO MAC & MAC HYDRODEMOLITION SERVICES INC.

Suite D-13, 301 West Holly Street, Bellingham, WA 98225 Tel: 1 800 665.7772

• Fax: 1 800 661.1178 Email: info@macandmac.com State of Washington Contractor License #MACMAHS996NB State of California Contractor License #800844

• 6 months prior to commencing Hydrodemolition submit superintendent name for security clearance

• 2-3 months (to be determined) prior to commencing Hydrodemolition Mac & Mac superintendent arrives onsite

• 2 -3 months prior to commencing Hydrodemolition submit crew names for security clearance

• 3 weeks prior to commencing Hydrodemolition crew arrives for Security, Fitness-Fo'r-Duty, Health Physics, Badging, Setup equipment,

• 3 weeks prior to commencing Hydrodemolition, Hydrodemolition power packs, tracks, manipulators/robots, all accessories and supplies arrive on site.

• 3 weeks prior to commencing Hydrodemolition all wastewater equipment, tanks, pumps arrive on site

• 3 weeks prior to commencing Hydrodemolition all vacuum truck units arrive on site THIRD WEEK BEFORE COMMENCING HYDRODEMOLITION

• Crew clearance completed (4 days)

• Stage Hydrodemolition power packs in Staging area approx. 400' from CTMT

• Stage and Assemble wastewater treatment facility in Staging area approx. 400' from CTMT SECOND WEEK BEFORE COMMENCING HYDRODEMOLITION

• Run High Pressure lines to CTMT location

• Run Wastewater lines from CTMT to Staging area approx. 400' from CTMT

• Run fresh water line from source to Hydrodemolition power packs in staging area approx. 400' from CTMT

• Install trash pump at containment bin to pump water to treatment facility approx.

400' from CTMT

• Install piping from treatment center to settling pond

• Build berm around equipment in staging area ATTACHMENT Z24R0 Page 5 of 7

PCHIEI'.C Exhibit 2 ENGINEERING CHANGE pag0 04 6RO MAC & MAC HYDRODEMOLITION SERVICES INC.

Suite D-13, 301 West Holly Street, Bellingham, WA 98225 Tel: 1 800 665.7772 9 Fax: 1 800 661.1178 Email: info@macandmac.com State of Washington Contractor License #MACMAHS996NB State of California Contractor License #800844 ASSEMBLE HYDRODEMOLITION TOWER

" Assemble Tower on the ground outside of compound - small (60 ton) crane required for 3 days and a 8,0001b forklift

• Lift Assembled Tower onto chipping platform - crane required

• Bolt Tower Guide Legs onto chipping platform

" Run all hydraulic (water soluble oil), electrical, and pressure lines from Power Pack located outside of compound to Tower. (run lines under fence)

• Hookup high pressure hoses, hydraulic and electrical lines to Hydrodemolition manipulators (Manipulators are attached to the track. Track is attached to Tower)

• Place 125 ft. manlift in position

" Mount Hydrodemolition Control box in 125 ft. manlift bucket (Operator/Technician location / station)

• Test High pressure lines, electrical and hydraulic lines and controls

• Place 8' x 20' (2-8x1 0) sheets of steel on platform against reactor wall for testing system

• Test: Tower / Track system, High pressure system, hydraulic and electrical controls ONE WEEK BEFORE COMMENCING HYDRODEMOLITION

• Complete projects (if any) not completed in week 2

" Fine tune all equipment

• Standby ready to begin Hydrodemolition 3 days prior to commencement date and time.

HYDRODEMOLITION COMMENCED

• Cutting Concrete removing 13% (13% of total) 4 Hours

" Remove rebar 12 Hours by others

• Cutting Concrete removing 17% (30% of total) 6 Hours

• Remove and plug tendons 12 Hours by others

• Cutting Concrete removing 23% (53% of total) 8 Hours

• Cutting Concrete removing 24% (77% of total) 8 Hours

• Cutting Concrete removing 13% (90% of total) 4 Hours

• Cutting Concrete removing 10% (100% of total) 4 Hours ATTACHMENT Z24R0 Page 6 of 7

PC"I",EftG Exhibit 2 ENGINEERING CHANGE pageO O6JS 6 RO MAC & MAC HYDRODEMOLITION SERVICES INC.

Suite D-13, 301 West Holly Street, Bellingham, WA 98225 Tel: 1 800 665.7772 e Fax: 1 800 661.1178 Email: info@macandmac.com State of Washington Contractor License #MACMAHS996NB State of California Contractor License #800844

• Cutting concrete perimeter clean up allowance 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />

• Hydrodemolition Equipment Demob 2 Days

" Water Treatment Demob 4 Days At all times Mac & Mac's project superintendent will keep Progress Energy representatives aware of our project progress and status.

ATTACHMENT Z24R0 Page 7 of 7

FM 7.2 Exhibit 3 page 1 of 1 10/28/2009 Interview Dave McNeill on phone Present: Dave McNeill (Mac&Mac, Vancouver), Craig Miller, Chong Chiu, Patrick Berbon Hydrolazing uses high-pressure pumps (triplex) with plungers (3 cylinders per pump).

Have X-Y machine on the platform.

Using 6 pressure pumps (1 pump per nozzle).

17,000-17,500 psi water pressure.

Flow rate 40-45 gallons/minute/nozzle.

Running 2 x 3 nozzles at the same time (3 nozzles per head, 2 heads).

Nozzle rotates at 500 rpm and projects water at a 5 degrees angle around the axis of rotation. Spin rate can be adjusted from 250 to 1,000 rpm. Was fixed at 500 rpm here.

Cut about 4 feet wide per head (total width of cut about 8' per pass).

Travels 1 ft/s along the beam, then move up 1.5 in, travels back 1 ft/s.

Each pass cuts lin to 1.5in deep.

Nozzles are 7 inches apart.

Water is taken from Progress large holding tank. It is pumped up from the tank and filtered to 1 micron.

It is recovered and re-filtered at the end (not recycled, dumped in settling pond after use).

Supply water is usually around 60 F. it was 85 F in this case. The pumping added an additional 25 F so that the water exited the nozzle around 110 F.

Mac&Mac works on many bridge decks. First nuclear project for the company.

Their in-house calculations for 17,000 psi, 500 rpm rotation, 40 gal/min water, lft/s travel, shows a force on the wall of 100 psi.

Nozzle is 1/8 inch.

First nozzle is 2-4 in from the wall, second nozzle is 3-5 in, third nozzle is 4-6 in (nozzles are in same plane, but distance increases as material is removed by each nozzle).

Takes approximately 35 min for one pass.

Pump is diesel powered (1,800 rpm), runs at 500 rpm.

Pistons are 1.5 in diameter, and move back-and-forth at 500 rpm.

FM 7.2 Exhibit 4 page 1 of 1 10/29/2009 Interview Bob Nettinger at American Hydro Present: Chong Chiu, Dan Fiorello (Exelon), Partha Ghosal (Southern Company), Patrick Berbon Bob Nettinger is with American Hydro. They are a competitor company to Mac & Mac, who performed the hydro-blasting for the CR3 containment.

They have done 7 post-tensioned containments.

They use 6 HP pumps, 2 robots.

Rotating jets lead to a better cut.

20,000 psi water, 150 gal/min/nozzle.

Use a plunger pump.

Wayne Younger (also works at American Hydro) would know the numbers for vibration and rpm.

Tower is 50ft high, can move on the platform, 4-wheel vehicle, 6ft wide cut top to bottom and back, 25ft from the wall.

1.5 inches deep cut per nozzle.

Nozzle is 6 inches from the wall.

They use nozzle extensions to get closer to the wall as they hydro-blast.

Use potable water as input into the pumps.

They are starting at TMI on Sunday, 11/1. John Piazza, structural engineer, senior design engineer on SG replacement at TMI.

Wayne Younger and Bob Nettinger called back later. They require PII to sign a NDA before giving additional information. It seems there is a lawsuit going on between American Hydro and Mac & Mac.