2008-04-28_port everglades inlet sand bypass - technical rev

7/31/2019 2008-04-28_Port Everglades Inlet Sand Bypass - Technical Rev

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olsen associates, inc. March 2008 Port Everglades Inlet Sand Bypass

2008, Contract Drilling & Blasting LLC

TECHNICAL REVIEW:

ROCK EXCAVATION METHODS FORPORT EVERGLADES INLET SAND

BYPASS


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2008, Contract Drilling & Blasting LLC i

TABLE OF CONTENTS

SECTION 1 - EXECUTIVE SUMMARY .......................................................................1:1

SECTION 2 - GENERAL..............................................................................................2:1

2.1 Scope of Work ...............................................................................................................2:1

2.2 Review Team .................................................................................................................2:12.2.1 Company Experience ..................................................................................................2:12.2.2 Team Members ...........................................................................................................2:2

SECTION 3 - PROJECT INFORMATION....................................................................3:1

3.1 Background ...................................................................................................................3:1

3.2 Project Allowable Depths .............................................................................................3:1

3.3 Site Conditions..............................................................................................................3:13.3.1 Surface Conditions ......................................................................................................3:13.3.2 Subsurface Conditions ................................................................................................3:2

SECTION 4 - ROCK EXCAVATION METHODS FOR MARINE CONSTRUCTIONPROJECTS..................................................................................................................4:1

4.1 Marine Excavation Equipment .....................................................................................4:1

4.2 Mechanical Rock Excavation .......................................................................................4:2

4.3 Rock Excavation with Pre-Treatment..........................................................................4:24.3.1 Punching ....................................................................................................................4:24.3.2 Surface Blasting ..........................................................................................................4:34.3.3 Drilling..........................................................................................................................4:44.3.4 Drilling and Blasting.....................................................................................................4:5

SECTION 5 - DISCUSSION.........................................................................................5:1

5.1

Pre-treatment Options ..................................................................................................5:1

5.1.1 Controlled Drilling and Blasting ...................................................................................5:15.1.2 Permits & Licenses Required ......................................................................................5:25.1.3 Coordination ................................................................................................................5:2

5.2 Special Considerations ................................................................................................5:35.2.1 Private Citizens............................................................................................................5:35.2.2 Protected Marine Species ...........................................................................................5:45.2.3 Structures ....................................................................................................................5:4


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2008, Contract Drilling & Blasting LLC ii

5.2.4 Vessel Traffic...............................................................................................................5:7

5.3 Environmental Effects: Mitigation & Protective Measures........................................5:75.3.1 Ground Vibration .........................................................................................................5:75.3.2 Air Blast Overpressure ..............................................................................................5:105.3.3 Flyrock.......................................................................................................................5:10

5.3.4 Noise .........................................................................................................................5:105.3.5 Underwater Blast Pressure........................................................................................5:105.3.6 Marine Species Protection Program..........................................................................5:11

5.4 Relevant Past Marine Construction Projects ...........................................................5:125.4.1 Port of New York / New Jersey..................................................................................5:125.4.2 Miami Harbor, Florida................................................................................................5:135.4.3 San Juan Harbor, Puerto Rico...................................................................................5:14

SECTION 6 - CONCEPT DRILLING & BLASTING PROGRAM .................................6:1

6.1 Design of Test Blast Program......................................................................................6:2

6.2 Production Blast Plan...................................................................................................6:2

SECTION 7 - CONCLUSIONS.....................................................................................7:1

SECTION 8 - ADDITIONAL WORK.............................................................................8:1

SECTION 9 - LIMITATIONS OF REPORT ..................................................................9:1


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2008, Contract Drilling & Blasting LLC 1:1

Sec t ion 1 - E X E C U T I V E S U M M A R Y

Contract Drilling & Blasting LLC has been subcontracted to review the available information andprovide guidance on the preferred method of excavation of rock for the construction of the sand

bypass at Port Everglades Inlet.It is estimated that as much as 280,000 cubic yard of rock may have to be removed for theconstruction of the sediment trap in the Port Everglades Sand Bypass project. It is generallyunderstood that rock stronger than 6,000 psi cannot be economically dredged without pre-treatment of the material. The largest equipment available in the North American market canefficiently dredge material up to 4,000 psi in strength without pre-treatment. However, for mostof the dredging equipment, rock stronger than 2,000 psi will have to be pre-treated to enableefficient dredging of the seafloor. Core boring data presently available indicates that most of therock found below -30 feet MLW (-32 feet NAVD88) will require pre-treatment.

Drilling and blasting of the bedrock is the most economical and most efficient pre-treatmentmethod. Controlled blasting techniques can be used to accurately create the desired

dimensions of the proposed sand trap and at the same time limit any potential adverse impacton the immediate environment by the blasting activities.

The review includes a discussion of the process to develop an effective drilling and blastingprogram for this project, with its limitations and potential benefits. More accurate informationabout the rock quantity and hardness in the proposed project location, and guidance on theenvironmental limitations such a blast induced vibrations which may be placed on the project,are essential in proceeding with detailed engineering of a drilling and blasting program for pre-treatment of rock.


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Sec t ion 2 - G E N E R A L

2.1 SCOPE OF WORK

Broward County issued a contract to Olsen Associates, Inc. for the second phase of the PortEverglades Inlet Sand Management Feasibility and Engineering Study RLI# 022100-RB in2006. As part of this study, Contract Drilling & Blasting LLC (CDB) has been subcontracted toreview and provide guidance on the preferred method of excavation of rock for the constructionof the sand bypass at Port Everglades Inlet. The Technical Review includes the following:

A summary of the existing geological and geotechnical data to identify the areas whereblasting could be anticipated for excavation to a depth of -45 feet MLW (-47 feet NAVD)1.

The review of the geological and geotechnical data will consider a five footencroachment depth for rock to elevation -50 feet MLW (-52 feet NAVD).

A discussion of the relative cost and likely outcome of various rock excavation methodsfor marine construction projects, with reference to past projects with relevance to the

proposed construction of the sand trap. The technical, environmental, regulatory, social and political issues related to blasting

are discussed, with emphasis on special considerations and protective measures.

The typical process to develop a Blast Plan is discussed. The Blast Plan ensures thatdrilling and blasting activities are executed in a safe and efficient manner, with dueconsideration and protection of private citizens, marine wild-life, structures, infrastructureand marine vessels in close proximity to the project area. A detailed and project-specificBlast Plan can be developed once specific project conditions and requirements areknown.

2.2 REVIEW TEAM

This Technical Review of the rock mostly likely to be encountered in the project area andguidance on the preferred method of excavation of rock, were conducted by personnel atContract Drilling & Blasting LLC (CDB), located in Jacksonville, Florida.

2.2.1 Company Experience

CDB excels in managing blasting programs and vibration control programs for specialty marineand land-based infrastructure construction projects and has often been retained as the primarydrilling, blasting and seismic consultants.

Since its inception in 1985, CDB has successfully completed numerous major navigationchannel and harbor expansion projects in locations from North America and the North Sea toCape Horn. The project list includes the Port of New York/New Jersey, Port of Wilmington, Port

of San Juan in Puerto Rico, Port of Freeport in the Grand Bahamas, and Miami Harbor, Port ofTampa and Port Manatee in Florida. Our customer list includes major international dredging

1 The geotechnical information collected for this project was originally referenced to the mean low water (MLW) datum at PortEverglades Entrance. Project design and specification is based upon the North American Vertical Datum of 1988 (NAVD88). Atthe NOS Port Everglades Lake Mabel Station (ID: 8722951), it is reported that NAVD88 is 2.15 feet above MLW. For thepurposes of this report, reference is made to both datums, where appropriate, and it is assumed for discussion that thedifference between the two datums is 2 feet.


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companies, such as Great Lakes Dredge & Dock Company, Weeks Marine, Donjon Marine,Boskalis and Bean Stuyvesant. A partial project listing is shown in Addendum B.

2.2.2 Team Members

The review team which worked on this review of the preferred method of rock excavation for thePort Everglades Sand Bypass consisted of the following members:

Albert vanNiekerk PhD PE Principal / Senior Blasting Consultant

Mary Gray Senior Vibration Consultant

Ralph Reese Senior Blasting Engineer

Adam Gray EIT Blasting Engineer / Seismic Engineer


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Sec t ion 3 - P R O J E C T I N F O R M A T I O N

The state of Florida adopted the Port Everglades Inlet Management Program in 1999 toimplement future mechanical bypassing of sand to reestablish littoral drift at the Port Everglades

Entrance. Olsen was selected by the state to perform a feasibility study on implementing a sandbypassing program and different design concepts have been evaluated.

3.1 BACKGROUND

The concept project (Alternative 4) under review here consists of the construction of a sand trapon the north side of the entrance channel to Port Everglades. Associated elements of the projectinclude modifications to the existing north jetty and removal of a portion of the spoil shoal to thenortheast of the entrance channel. The sand trap will be excavated to elevation -45 feet MeanLow Water (MLW) (-47 ft NAVD).

CDB conducted a review of the available information directly relevant to this project. Theprimary goal of evaluating these data is to identify areas where blasting may be required to

dredge the sand trap to project depths.

3.2 PROJECT ALLOWABLE DEPTHS

For a final removal depth of -45 ft MLW (-47 ft NAVD) it will be necessary to allow the followingproject depths:

MLW NAVD

Excavation Depth -45 ft -45 ft -47 ft

Over-depth 2 ft -47 ft -49 ft

Over-depth in Rock 2 ft -49 ft -51 ft

Additional Tolerance 1 ft -50 ft -53 ft

3.3 SITE CONDITIONS

Down-To-Earth Geotechnical Consulting, Inc. (D2E) conducted a field exploration program forOlsen to determine the site conditions in the proposed area of the sand trap.

3.3.1 Surface Conditions

The project is located at the Port Everglades Inlet in Fort Lauderdale, Florida. The aerial picturebelow shows the position of the proposed project location relative to its surroundings. Thegeneral project area is bounded by the Port Everglades to the west, multi-family high-risecondominiums and single-family residences to the north, the Naval Surface Warfare Center

South Florida Testing Facility and John U. Lloyd Beach State Park to the south, and the AtlanticOcean to the east. The southern boundary of the proposed sand trap is the northern boundaryof the Port Everglades Federal Navigation Channel which provides access to Port Everglades.

Tidal currents through the Port Everglades Inlet has been determined to reach maximumspeeds of approximately 2.4 ft/sec. Observations of surface currents showed that flood tidecurrents seemed to be strongest in the center of the entrance channel. Although the tidalcurrents are predominantly east and west, the center channel currents also have a strongnortherly component primarily seen during the ebb cycle.


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Figure 3-1: Aerial Overview of Project Area

Water depths in the proposed project area range from 6 to 7 feet near shore to as much as 20feet in the central portions of the proposed sand trap.

3.3.2 Subsurface Conditions

Eleven core borings sampled from the locations shown on the aerial view above, wereanalyzed. The results showed 3 distinct layers in the ocean floor:

Layer I (bottom at -13 to -23 feet MLW) (-15 to -25 feet NAVD): Fine to medium sand,with silt, shell and limestone fragments;

Layer II (bottom generally at -25 to -34 feet MLW (-27 to -36 feet NAVD), maximum at-44 feet MLW (-46 feet NAVD)): Sandy limestone and limestone; and

Layer III (extends to bottom of borings at -55 feet MLW (-57 feet NAVD)): Shellysandstone.

D2E concludes in their geotechnical report that mostly modest rock strength was encountered toa depth of -30 feet MLW (-32 feet NAVD). Below that elevation the rock becomes harder andexcavation of the material becomes a concern. For the purpose of characterizing the rock forexcavation, they reported typical rock characteristics for rock at elevation above and below -45feet MLW (-47 feet NAVD) as follows:


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Above -45 feet MLW: Average rock strength is 1,821 psi and maximum strength is 5,100psi

Below -45 feet MLW: Average rock strength is 3,177 psi and maximum strength is 4,470psi


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Sec t ion 4 - R O C K E X C A V A T I O N M E T H O D S F O R M A R I N EC O N S T R U C T I O N P R O J E C T S

4.1 MARINE EXCAVATION EQUIPMENT

Removal of subsurface rock in marine construction projects such as navigation channelexpansion or harbor deepening, or in this specific case, excavation of a sand trap for the PortEverglades Inlet Sand Bypass project, can be accomplished utilizing construction equipmentand techniques specially adapted for marine environments. These projects are typicallyexecuted by dredging and marine contracting companies which specialize in this type of rockexcavation. The equipment available to them range from very large and powerful barge-mounted mechanical excavators and hydraulic cutter-head dredges to clam-shell dredges orsmaller excavators. A few points on the capabilities of the different types of dredging equipmentutilized in the marine contracting industry are noted in the table below.

Type of Dredge Capabilities NotesLarge excavator orback-hoe

Best-suited to dredge rock of6,000 psi or less without pre-treatment of the rock

Hydraulic cutter-suction Largest cutter-suction dredgescan economically dredge 3,000 to4,000 psi rock; typical cutter-headcan dredge 1,000 to 2,000 psirock

Could be limited by waterdepth and surf conditions

Small excavator orback-hoe

Limited to about 2,000 psi rock;can handle alternating stiff clays,

sand, and rock

Thick beds of even lowstrength rock are difficult

Clam shell Limited to rock of 500 psi or less Not efficient in areas wherethere is extensive rock

The determination of whether a dredge is capable of excavating the rock present in a projectarea without pre-treatment depends on the type of rock and associated sediments, the strengthof the rock, and the dredging equipment selected by the contractor and available at the time ofthe project. It is typically stated in the dredging industry that rock with an unconfinedcompressive strength of more than 6,000 psi must to be pre-treated by drilling and blasting priorto dredging. Most equipment requires pre-treatment when rock strength is over 2,000 psi.

However, when limited quantities of hard rock exist in a project area, it may be more economicaloverall to slow down production and incur the additional cost for wear and tear, by dredging thehard sections without pre-treatment.

Even for equipment that may be capable of dredging the material without pre-treatment, there isan optimal cost for the overall production cycle (mobilization, pre-treatment, excavation anddisposal) which depends not only on the available equipment and rock strength, but also on theproject location. For example, if a drill boat is available in the vicinity of the project location,drilling and blasting may be utilized as a pre-treatment method to increase the productivity of the


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dredging equipment available for the project. Or it might be too expensive in the total costanalysis to mobilize pre-treatment equipment and personnel and a large and powerful excavatormay be used to free-dig the harder material.

4.2 MECHANICAL ROCK EXCAVATION

The known geologic conditions and the strength of rock sampled in the areas of the PortEverglades Inlet suggest that all but the largest mechanical excavator may require pre-treatment prior to dredging. Hydraulic cutter-heads may be strong enough excavate the rock,but the presence of associated silty sand and lenses of hard rock may prove the equipment tobe unproductive in the Port Everglades Inlet. If dredging equipment has to work in a surf zone,its productivity could be adversely affected.

Based on the information in the table on the previous page, we conclude that many zones of therock within the proposed excavation area can be excavated by conventional mechanical means,particularly at excavations above elevation -30 feet MLW (-32 feet NAVD). However very hardzones should be anticipated as suggested by the laboratory test data and consequently it mightprove to be more practical and cost-effective to pre-fracture those zones of the rock by pre-treatment. Based on the field and laboratory test data these hard zones are expected to bemore common below elevation -30 feet MLW (-32 feet NAVD).

4.3 ROCK EXCAVATION WITH PRE-TREATMENT

Depending on the rock type and hardness, pre-treatment may be required prior to dredging,either to make it possible to dredge the fractured material with the dredging equipment availablefor the project, or to improve the dredging efficiency or operating cost of equipment that mayhave been able to dredge the rock without pre-treatment.

Several techniques have been developed for the pre-treatment or pre-fracturing of rock. Therelative order-of-magnitude cost for pre-treatment per cubic yard of rock is listed in the tablebelow for some of the most common techniques.

Pre-Treatment TechniqueOrder-of-Magnitude

Unit Cost ($/cubic yard)

Punching > 1,000

Surface blasting 375

Drilling only: Line drilling orSwiss Cheese drilling

150

Controlled drilling & blasting 20 30 in standard projects

15 20 in mega-projects

4.3.1 Punching

The pre-treatment technique of punching is sometimes used to fracture rock in preparation fordredging. It involves dropping a heavy steel bar with a chisel shaped bottom end through aguide mounted on a barge or pontoon. The chisel then punches holes in the rock, typically 1 to2 feet deep. The end result is a series of square holes across the removal area and some


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fracture planes in the rock mass, with limited improvement in ease of excavation. The fracturedand broken rock in this layer has to be excavated for the next series of punching to beaccomplished. Alternatively, when a free face exists, the punch can be used to progressivelychisel the rock into the void created by prior excavation of the chiseled material. The figurebelow depicts the relative size and distribution of the punch holes in a given removal area.

Figure 4-1: Relative Size and Distribution of Punch Holes across Removal Area

A common problem associated with this technique is for the punch to penetrate the variousstrata, with the broken rock below a harder layer locking the punch, thereby making extractiondifficult, if not impossible. A contractor tried this methodology in Miami Harbor in the 1990s,sometimes taking days to extract their punch. This contractor subsequently abandoned theproject. On a project in New York Harbor, in harder rock, productivity was extremely low - in theorder of 50 to 100 cubic yards per day and not cost effective.

4.3.2 Surface Blasting

Surface Blasting is a technique normally used to remove underwater obstacles such as highspots or boulders and can conceivably be utilized to pre-treat a mass of rock for dredging. Thistechnique involves placing specially designed explosives charges on the surface of the rock andthe objective would be for the explosives force to fracture the rock mass sufficiently to enabledredging of the broken material, or to improve dredging efficiency. One such product is calledQuick Dredge and is a shaped charge with a predetermined set-off distance from the rock. Thepicture below shows this product employed in underwater boulder blasting.

Figure 4-2: Quick-Dredge Charge Used in Boulder Blasting


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To effectively break the surface area of a given rock mass, these special explosives chargeshave to be placed relatively close together. Each charge would shatter a roughly conical holeapproximately 2 feet in diameter at the rock surface, tapering to 0 feet at a depth of 4 to 6 feet.The fractured material must then be excavated before the next lift can be treated andexcavated.

Figure 4-3: Relative Size and Distribution of Surface Blasting Charges across Removal Area

These charges have to be placed by a diver, which means that the underwater visibility must besufficient to accurately place the charges. The maximum speed of tidal currents through the PortEverglades Inlet has been determined to be approximately 2.4 ft/sec. This may add anadditional complication for a diver to position the charges and for the charges to stay in position.

4.3.3 Drilling

Drilling holes into the rock mass to be removed, can be employed as a technique to createfracture planes in the rock to enable or facilitate excavation. When a single row of holes isdrilled, the technique is called line drilling and when several rows of holes are drilled across aremoval area, the method is sometimes referred to as the swiss cheese technique. Holes haveto be drilled very close together to be effective and are usually only separated by 9 to 15 inches.

The holes also have to be of a relatively small diameter and should be drilled a minimum of 24inches below removal depth. The picture below depicts the relative size and distribution of drillholes required to employ the swiss cheese technique for pre-treatment of rock across aremoval area.

Figure 4-4: Relative Size and Distribution of Drill Holes across Removal Area in 'Swiss Cheese'Drilling as a Pre-Treatment Technique


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The vast number of holes required usually means that drilling capacity becomes a limiting factorin the execution of the project and that pre-treatment by drilling becomes a critical-path item.Since the excavation equipment is generally more expensive than drilling equipment, this isusually not a viable option for mass excavation.

The technique is typically employed as line drilling only under special circumstances, such as

when rock removal is required close to a sensitive structure such as a dock or a bridge pier.4.3.4 Drilling and Blasting

It is well known in the mining and construction industry that the most efficient method ofbreaking rock is by means of drilling and blasting. The technique is well established and thescience behind it well understood also. In land-based infrastructure development, drilling andblasting is utilized as a method to fracture rock in-situ for removal by excavation equipment.

Underwater infrastructure development brings several additional challenges to a constructionproject, but a special adaptation of controlled drilling and blasting techniques for submarineapplication has been used with success for many years across the world. More specifically,underwater drilling and blasting has been used successfully in major navigation channel andharbor expansion projects in several ports on the east coast of the USA and in the Caribbean.

Some projects of relevance to the proposed Port Everglades Sand Bypass are discussed inmore detail in another section of this review.

The schematic below shows how Drilling and Blasting is utilized in the excavation cycle to pre-treat the rock for removal by dredge in the Port of New York / New Jersey.

Figure 4-5: Typical Arrangement for Controlled Drilling & Blasting as Pre-Treatment Technique forDredging (Port of New York / New Jersey Project)


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Because of the very efficient utilization of the energy from the explosives, blast holes can bedrilled relatively far apart (relative to the previous techniques described above). A typical blastpattern would have blast holes of 3 to 5 inches in diameter drilled approximately 8 to 14 feetapart in rows across the rock removal area. The holes are drilled deeper than the required

removal level to ensure that all the fractured material can be excavated efficiently to thespecified elevation. The drawing below shows the relative size and distribution of holes in adrilling and blasting program designed for submarine pre-treatment of rock.

Figure 4-6: Relative Size and Distribution of Blast Holes across Removal Area in Drilling andBlasting as a Pre-Treatment Technique

Explosives contain two useful types of energy generated by the explosive reaction, shockenergy and gas energy. Both types of energy are release during the detonation process;however the Blasting Engineer can select explosives with different proportions of shock or gasenergy depending on site specific rock conditions.

There are five general stages of breakage that occur during the work effort process, afterdetonation of a confined explosive.

Stage 1 A shock wave conditions the rock by causing micro fracture in the borehole orelongation of existing or natural weak planes. This process is less than 15% of thebreakage results.

Stage 2 Once the initial shock wave has passed, the expanding gases causepressurization of the bore hole which drives natural or radial cracks through the rock untilsome form of resistance or relief dissipates the process.

Stage 3 The rapid oxidation of the burning process causes high pressure gases tocontinue to pressurize the elongated cracks until released or vented in movement, thisprocess results in about 80% of the breakage.

Stage 4 Rock movement begins with the flexural failure as a result of the bending of

the rock mass and the tensile strength having been exceeded.

Stage 5 A collision effect further breaks the rock mass because of one mass collidingwith another during the delayed directional propagation.

The amount of energy required to break rock is different if the rock is solid and massive ratherthan closely spaced weak and seamy. The joints bedding plane and intermittent layers are moreimportant than the tensile strength of the rock matrix. Examination of the visual seams in thecore samples can indicate if a blasting problem will be encountered.


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In reviewing the in-situ geology, items of interest are blow counts, compressive strengths androck-quality designation (RQD), which is the number of naturally occurring fractures per foot ofcore run (4 inches or more) expressed as a percentage of the length of core run. The in-situgeology values will determine the dredgability of the bottom materials along with the need forpre-treating based on the excavation equipment. The type of dredging equipment, excavator,hydraulic dredge, or clam bucket will respond differently to the RQD based on the strength and

massiveness of the joints.


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Sec t ion 5 - D I S C U S S I O N

5.1 PRE-TREATMENT OPTIONS

It is expected that for the hard materials found below about -30 ft MLW (-32 ft NAVD) at theproposed Port Everglades sand bypass sediment trap area, pre-treatment by drilling andblasting may be required for a viable solution to the construction of the sand trap. At a minimum,this option reduces the risk and uncertainty regarding removal of very hard materials, andprovides the confidence that ultimately there will be a method available to remove thesematerials irrespective of whether or not a large cutter-suction dredge can be used withoutblasting. In addition, it allows several other construction options to be considered by contractorscompeting for the work, including using smaller excavators or less powerful cutter-headdredges.

The other pre-treatment techniques discussed in an earlier section of this review document maybe utilized in special situations. As an example, surface blasting may be utilized to remove highspots or boulders, and line drilling may be utilized to create a buffer zone close to sensitive

structures or for smooth blasting of the outside perimeter of the sand trap.The total volume of rock to be removed in the proposed sand trap location is estimated at280,000 cubic yards and the spatial extent of rock area to be excavated is approximately210,000 square foot. Typically, drilling and blasting efficiency in submarine blasting is mainly afunction of the surface area to be blasted. In general, rock can be pre-treated with full-scaleproduction drilling and blasting at a rate of 2,500 to 5,000 square feet per day. This means thatapproximately 40 to 85 blasts will be required for blasting of the proposed sand trap. Typically,only one blast can be completed per day, although it may be possible to sometimes have twoblasts per day, depending on other restrictions such as environmental requirements for theproject. Some smaller blasts may be required closer to the most sensitive structures, dependingon the vibration limitations for the project. This may increase the number of blasts. Based on theabove, it is anticipated that between 30 and 90 blast days will be required if all the rock in the

project area has to be pre-treated by blasting.

5.1.1 Controlled Drilling and Blasting

From the discussion earlier in this report, it is clear that blasting releases a tremendous amountof energy. Some of this energy is transmitted through the surrounding material as a shock waveand may cause ground vibration. A special blasting technique called Controlled Drilling andBlasting is utilized to minimize the magnitude and impact of vibrations and air overpressureinduced by blasting activity. In this technique, blast holes are timed with very accurate delays inthe initiators to detonate individually, thereby reducing the quantity of blasting agents orexplosives going off at any one time. The size of blast hole and hence the quantity of explosivesthat can be used in a single event, is determined by the allowable ground vibration and air blastoverpressure at locations of concern. The blast is also designed to provide maximum relief for

rock movement. (An example of the contents of a typical Blast Plan for submarine blasting isincluded in Addendum D.) Sometimes other environmental restrictions such as the protection ofmarine species, may also apply, which must then be incorporated into the blast design.

In this well-controlled blasting environment, ground vibration and air overpressure are measuredat critical points in the surrounding area and the data is fed back into the design of the nextblast, to always ensure that blasting is conducted with the impact on the environment controlledwell within allowable limits.


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5.1.2 Permits & Licenses Required

Before blasting operations commence, regulatory agencies will have to be contacted in order toobtain all of the proper licenses and permits for the specific coordinated blasting work effort.

The following Permits and Licenses to purchase / use explosives will be required:

Bureau of Alcohol, Tobacco and Firearms (AFT Federal Permit)

US Coast Guard (USCG) Hazardous Materials Permit

State of Florida (User Permit & Blasters License)

Broward County (Blasters License)

City of Ft. Lauderdale (Fire Prevention Permit and Zoning Board blasting bond)

The approval of a Drill Boat for use in Port Everglades, Florida will require the followinginspections prior to use.

ATF (storage, use)

USCG (hazardous materials, storage)

State of Florida (storage, use)

City of Ft. Lauderdale (storage, use)

5.1.3 Coordination

All Drilling and Blasting activities will require coordination with the following:

ATF

Local Law Enforcement Agencies (Broward Sheriff Office)

Port Facilities Security

Division of State Fire Marshall, Bureau of Fire Prevention

Broward County

City of Ft. Lauderdale

United States Coast Guard

MSO (Marine Safety Office)

Florida Marine Patrol

VTS (Vessel Traffic Services)

Local Law Enforcement Agencies and the USCG will determine the Means and Methods fortransportation of products from the local distributor to the Drill Boat at the loading facility.

Local Law Enforcement Agencies will determine whether a police escort will be required for

transportation through the city.Port Everglades will determine what security measures will be required at the Port facility.

The USCG will determine what security measures will be taken once the products are on boardthe drill boat.

Product deliveries are normally scheduled to take place between 4:00 a.m. and 6:00 a.m. toreduce the public and Port impact to traffic and work efforts.


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Product storage quantities are generally based on one weeks usage to minimize thetransportation impact on the public, Port facility, local police and USCG.

The Blasting Detonations will be scheduled to take place 2 hours after sunrise and one hourbefore sun set with a 2 hour window of opportunity and an extensive call list for interestedparties and regulatory agencies.

The Marine Mammal Protection Program will govern the actual time of detonation once the DrillBoat is ready to blast.

5.2 SPECIAL CONSIDERATIONS

5.2.1 Private Citizens

Human response to activities outside of the ambient environment has been extensivelydocumented, and it is well known that unanticipated incidents tend to have a more dramaticeffect on the human response.

A good analogy is the JND (just noticeable difference) phenomena. An example: one is drivingin their car listening to the radio. Enjoying a particular song, the user turns the volume dial

incrementally over a short period of time to a louder volume. They get home, they turn their caroff, and the next day when they start their car, they are startled by the loudness of the radiosvolume set by the previous days drive.

JND occurs in many other areas of the urban environment, but the human body has beenconditioned to rule these things out. When the telephone rings, one usually does not jump,because it is an environmental variable that we are conditioned to. Vibrations from blasting arenot something the human body has been conditioned to, because it is a very infrequentoccurrence for a relatively long duration of time. The Vibration Scale by Konya in the schematicbelow depicts the relative intensity of vibration caused by everyday occurrences in ourenvironment.

Figure 5-1: Konya's Environmental Vibration Scale

The following schematic depicts on the same scale, the relative effect of blast induced vibrationon different groups of the population, objects and structures. A discussion of typical vibrationlimits imposed by regulatory agencies follow later and put the chart below in perspective.


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Figure 5-2: Konya's Blast Effects Scale

5.2.2 Protected Marine Species

Southeast Florida is home to several threatened and endangered marine species such asmanatees, sea turtles, and, and the small tooth sawfish. Submarine blasting can adverselyaffect these and other marine animals. Therefore, special consideration must be paid to ensuretheir safety and protection during construction of the proposed sand trap. It has been shown in arecent project of similar nature in South Florida (Miami Harbor Deepening 2006) that a MarineSpecies Protection Plan can be successfully implemented and executed to protect and minimizeadverse effects marine species.

A Marine Species Protection Plan will be discussed in more detail in a later section in thisreport, but consist of two main elements: wildlife monitoring before, during and after blasting,and mitigation of the potential impact of blasting. In order to minimize the potential exposure of

marine species to construction activities, blasting may be preferred during times when thelowest number of a specific species may be present in Port Everglades. As an example, blastingactivities may be preferable during the months from March to November when manateepopulations are lowest in the area. Conversely, consideration may also need to be made for thepotential presence of sea turtles during the summer months. Coordination with Federal andState resources agencies will be necessary to determine construction windows and methodsthat will be the least impactive to marine species. In any event, blasting should only beperformed during daylight hours from two hours after sunrise until one hour before sunset tofacilitate visual observation of the presence of marine mammals in the area.

The scope of a Marine Species Protection Plan will be determined in collaboration with marineenvironmental specialists, Federal and State regulatory and resource agencies, and the blastingspecialist.

5.2.3 Structures

Several existing structures are adjacent to the project area and within a zone where effects ofblasting can be expected. The aerial view below shows a 1,500 ft Vibration Impact Distance(VID), which is the typical area of concern specified by the US Army Corps of Engineers forprojects that include blasting. The structures within the 1,500 ft zone at Port Everglades arediscussed in more detail in a report by D2E.


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Figure 5-3: Aerial Overview of Project Area Showing Impact Zone of 1,500 ft

(a) Residential and Commercial Structures

The closest structure to the proposed location of the sand trap is the Points of the AmericasTower number II. The table below shows the primary structures of concern and their distanceaway from the closest point of the project area.

StructureDistance from

Project Area (ft)

Points of America Tower I 630

Points of America Tower II 337

Sky Harbor East 735

North Seawall 675

Naval Surface Warfare Center 910


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(b) Critical / Historical Structures

Tidewater Atlantic Research, Inc. (TAR) conducted an archaeological and historical marinesurvey of the Port Everglades Sand Bypass Project on behalf of Olsen and Associates, Inc.

Analysis of the data revealed 174 small magnetic/acoustic anomalies. TAR determined that

fourteen of the anomalies had signature characteristics consistent with shipwreck material. It isthe opinion of TAR that since none of the targets are located within the dredge area, theproposed project will have no adverse effect on cultural resources listed or eligible for listing inthe NRHP, or otherwise of historical or archaeological value. TAR recommended furtherinvestigation if the plans change to include targets.

(c) US Naval Surface Warfare Center

On the south side of the Port Everglades inlet is the South Florida Testing Facility (SFTF) whichis under the direction of the Naval Surface Warfare Center, Carderock Division (NSWCCD). Inaddition to structures on the surface, the SFTF has extensive submarine equipment that may bein close proximity to the proposed Port Everglades sand trap.

As stated on the web-site of the South Florida Ocean Measurement Center, the NSWCCD

facility provides the ability to monitor surface ship, submarine, and remote vehicle signaturesin the near shore environment. Multiple fixed in-water electromagnetic and acousticmeasurement sites at 10, 20 and 200 meters are controlled from a secure range house. Therange encompasses the Navy's only shallow and deep magnetic research and developmentranges, including submerged operations. The facility also offers a means to evaluate minedetection, countermeasures and mine response; perform acoustic measurements; and acquireradar cross section (RCS) and infrared signatures. Surface, air and submerged tracking areavailable on this controlled range. 20 and 200 meter bottom mounted acoustic Doppler currentprofilers provide continuous current monitoring on the range. There are also deep and shallowwater multiplexers allowing for installation of additional sensors on an "as needed" basis withoutthe large expense of running new cables

Submarine blasting may have an effect on such equipment. It is therefore recommended thatBroward County engage in dialogue with the US Navy regarding the sand bypass project andthe possible effects underwater blasting may have upon this facility and it associated submarineequipment.

(d) Seawalls

As stated clearly in other reports on this project by D2E the present condition of the seawallsnorth and south of the project area is poor. If these structures have to be protected in theirpresent state, it may place undue restrictions on the design of a blasting program for rock pre-treatment. If it is considered to replace these seawalls, this restriction will be lifted and mayfacilitate higher productivity during the drilling and blasting program. Construction of any newseawalls should be postponed until after the blasting program has been concluded.

(e) Proposed Jetty Extension

Any structure in close proximity to the blasting area may potentially be affected by blast inducedvibrations. As stated before, a well designed and executed Blast Plan will limit the effect ofthese vibrations, but they will be present during pre-treatment of rock by means of blasting. It istherefore recommended that consideration be given to the possibility of constructing theproposed jetty extension following completion of all blasting activities.


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5.2.4 Vessel Traffic

Hydraulic shock generated by detonation, and the rapid gas expansion in the work process ofthe explosives, creates a large gas bubble which in turn creates wave propagation. Hydraulicshock and wave propagation is the primary threat to vessel traffic. A relationship for safe vesselmooring can be determined based on results from previous Production Blasting and evaluationof the condition of the vessel. Results of the Blasting Program will confirm a safe vessel mooringdistance from the Blast Zone based upon the evaluation of the vessel condition.

5.3 ENVIRONMENTAL EFFECTS: MITIGATION & PROTECTIVE MEASURES

5.3.1 Ground Vibration

Ground vibration induced by blasting events starts as excess energy not utilized in breakingrock which is released from a confined explosives charge and dissipated in a radial mannerfrom the origin of the event. This vibration is typically of a low frequency ranging from 10 to 40Hz.

The main concern with underwater blasting, other than the inherent dangers that exist inexplosives work, is vibration. Present vibration standards have been established through more

than 75 years of research and test investigation by the U.S. Bureau of Mines (USBM).

The most commonly adapted Blasting Criteria, accepted industry wide, is USBM Bulletin 656.Particle velocity is considered to be the best measure of damage potential and the means ofdetermining safe vibration criteria. The unit of measure for peak particle velocity (PPV) is inchesper second (ips) or millimeter per second (mm/s).

Nichols, Johnson and Duvall, Blasting Vibration and Their Effects on Structures, U.S. Bureau ofMines Bulletin 656 (1971)

Safe zone - Less than 2.0 ips (50.8 mm/s)

Damage zone - Greater than 2.0 ips (50.8 mm/s)

The general assumption is that if the peak particle velocity is a measurement of damage it can

also be construed as a measurement of safety. In general, if damage is likely to occur at orabove a PPV of 2.0 ips, then a PPV measured below 2.0 ips indicate that damage is not likely tooccur. More recently damage has been defined as the threshold of cosmetic damage of themost superficial type, of interior cracking that develops in all homes, independent of blasting.

In a more recent study on structure response and damage from surface mining operations, theinterdependence between frequency and vibration and their influence on damage potential isdiscussed:

Siskind et al, Structure Response and Damage Produced by Ground Vibration from SurfaceMine Blasting, U.S. Bureau of Mines Report RI-8507 (1980)

Both USBM reports are frequently quoted. Other authors also published thresholds for potential

damage:Langefors, Westerberg and Kihlstrom, Ground Vibration in Blasting Parts 1-111, Water Power(1958)

No damage - Less than 2.8 ips (71.12 mm/s)

Fine Cracks - 4.3 ips (109.22 mm/s)

Cracking - 6.3 ips (160.02 mm/s)

Serious Cracking - 9.1 ips (231.14 mm/s)


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Edwards and Northwood, Experimental Blasting Studies on Structures, National ResearchCouncil, Ottawa, Canada (1959)

Safe zone - Less than 2.0 ips (50.8 mm/s)

Damage potential - 4.0 to 5.0 ips (101.6 to 127 mm/s)

The vibration energy from a blast event moves out from the source in all directions. If thegeology of the surrounding area was constant, vibration would be transmitted in the samemanner in all directions. If all other factors remained constant, theoretically at the samedistance, in any direction, the vibration level would be equal. In reality this condition rarely existsbecause changes in the earth structure will cause the transmission of the vibration to bedifferent. Frequency and vibration levels will be altered by the geologic structure, joints, dips andfaults.

Additional factors, such as the blast design can also contribute to directional vibration effectbecause of constructive and destructive waves canceling or accelerating one another. Modernblast techniques utilize a Test Blast Program to calibrate the environment and to develop apredictive model for minimizing the potential site specific impact from blast induced vibration.This process will be discussed further in the Test Blast Program section in this Review.

It is clear from the above discussion that it is generally accepted that vibrations levels below 2.0ips will not cause any damage to structures exposed to those vibrations.

(a) Test Blast Program

In advance of production level blasting, a Test Blast Program will be conducted in order to begina calibration of the vibration environment. This will include a blast, using the smallest chargeweight anticipated in design, at a point in the excavation area furthest from upland structures.During this test blast, an array of seismographs will be deployed in different directions and atdifferent distances away from the blast area and vibration data will be collected. With thisinformation, a site specific vibration model is created. This model takes into consideration thedistance the seismograph is placed from the blast, the charge weight per delay, and thevibration levels measured by the seismograph. The model is then used to predict vibrations for

future blast designs using the anticipated maximum charge weight per delay and distance to theclosest structure. In subsequent blasts during the Test Blast Program, actual blast data iscompared to the predicted data and calibration of the prediction model is continuously refined.

This Test Blast Program is then built up to the maximum production blast levels that would beencountered in full production mode. It will be at this point that the site specific vibration data willlend to a blast design that will be optimized for creating excavation material suitable for dredgingwhile minimizing any vibration impacts on the surrounding environment.

(b) Vibration Control Program

The Best Practice in the blasting industry in monitoring and mitigating the potential effects ofblast induced vibration on nearby structures is a well designed and executed Vibration ControlProgram. Such a program would consist of three main elements:

A survey of structures that could potentially be impacted, prior to the start of the blastingprogram;

Monitoring blast induced vibration levels at these structures during the course of theblasting program; and

An exit survey of the structures upon completion of the blasting program.

The purpose of the structural survey prior to the blasting program is to establish a baselinecondition for each structure within a pre-determined Vibration Impact Distance (VID) from the


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blast zone. This distance could be determined by the specifications for the project in question,or it can be calculated from the vibration limits for certain types of structures set by the projectowner. Special attention is paid to historic or critical structures and different vibration limits maybe specified for different types of structures.

Once the baseline condition for each structure has been established, the vibrations levels

resulting from ongoing blasting activities are measured at carefully selected locations. The aerialoverview of the project area below shows in green an example of selected seismographlocations. The actual locations will be determined as part of the implementation of the VibrationControl Plan.

Figure 5-4: Sample Seismograph Locations in Relation to the Project Area

These actual measurements of vibration levels at the seismograph locations are used toconstantly update the calibration of the environment, so that the most likely vibration level at anydistance away from the blast zone can be calculated with confidence. It is therefore possible toapproximate the maximum vibration level that a given structure would have experienced, eventhough vibration data may only have been collected at different locations. Provided that thevibration limit at a specific structure was never exceeded for the duration of the project, nodamage to the structure would be possible from blast induced vibrations.

Upon completion of the blasting program, an exit survey is performed on the structures todocument that no damage resulted from blasting activities.


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An important aspect of the successful implementation of a Vibration Control Program isdissemination of information related to the blasting project, its potential impact and mitigationmeasures to members of the public and business communities in close proximity to the project.Good public relations and open communication lines are important, since it can be proven toconcerned parties that the damage potential from blast induced vibrations can be mitigated byspecialist intervention in the execution of the blasting program.

5.3.2 Air Blast Overpressure

Upon detonation of a blast, a small portion of the energy not utilized in breaking rock is releasedas a pressure wave transmitted through the air. The intensity of this air overpressure or soundwave can be expressed in units of pounds per square inch (psi) or on a logarithmic scale indecibels (dB). Onset of cracks in standard glass window panes is seen at much higher dynamicoverpressure levels of 0.1 psi (150 dB). Some projects set limitations on air overpressure in thespecifications, typically in the range of 0.005 psi (124 dB) to 0.02 psi (137 dB). Sample wordingin the specifications may read as follows: The maximum peak positive air blast overpressure forany structures, vehicles, or vessels moored or underway, with glass windows shall not exceed0.02 psi.

The air blast overpressure resulting from submarine blasting is usually negligible because the

blast takes place several feet under water. Typically, the only sound from an underwater blastcomes from the surface initiation system (which can be mitigated by proper blasting techniques)and by venting to the surface of the water of large quantities of gas produced by the explosion.Monitoring and mitigation of air blast overpressure is usually included as part of the Vibration(and Air Blast Overpressure) Program.

5.3.3 Flyrock

Flyrock is not an occurrence with underwater blasting. The amount of water coverage over ashot inhibits the shot area from producing any type of projectile. There are methods ofcontrolling flyrock with controlled blasting techniques. These techniques allow for the rock to bedistributed into an area of relief, which can be considered a controlled distribution.

5.3.4 Noise

In marine blasting applications, noise from a blast is limited to the surface initiation system, andtechniques are used to inhibit or minimize air overpressure which can be translated as noise.Submerging the trunk line in the water reduces the air overpressure created from thedetonation, reducing the air overpressure.

5.3.5 Underwater Blast Pressure

The pressure pulse generated by underwater blasting can be significant, depending on theblasting technique employed. With Controlled Blasting, the quantity of explosives used insubmarine blasting is designed to the minimum quantity required to break the rock on theseafloor efficiently. Special timing techniques are used to control and minimize the number ofblast holes firing simultaneously, thereby minimizing the instantaneous pressure produced bythe blast.

As an essential element of the Marine Species Protection Program, a special blastingadaptation of Controlled Blasting called Confined Blasting is utilized to minimize the intensity ofthe underwater blast pressure. In this technique, an inert material such as crushed stone is usedto seal off or stem the blast holes in the submarine rock floor and contain the energy releasedby the detonation of the explosives in the blast hole inside the rock. The stemming of the blasthole serves a two-fold purpose: it makes the fracturing of rock more efficient by containing theenergy in the area where the work is required, and it allows a minimum of waste energy to betransmitted through the water in the form of a pressure pulse. Confined Blasting has been


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shown to reduce the intensity of the pressure pulse by 60% to 90% when compared to standardunconfined blasting techniques (Miami Harbor Deepening 2005/2006). This technique has beenused since the 1980s in New York, North Carolina and Puerto Rico to reduce the impact ofunderwater blasting.

5.3.6 Marine Species Protection Program

It was shown in the Miami Harbor Deepening project completed during 2005 and 2006, that aprogram to protect marine wildlife can be implemented and executed successfully whensubmarine blasting is employed as a technique to pre-treat the hard rock for dredging. Such aprogram has two key components:

Watch Plan (Observation and monitoring of marine species in the blasting zone, and in asafety zone and watch zone around the immediate blasting area); and

Mitigation Plan (utilizing special blast design techniques to minimize the potential impactof submarine blasting on marine species).

The Watch Plan is typically designed and executed by a specialist in the field of marine wildlifeprotection, whereas the Mitigation Plan is designed and executed by a submarine blastingspecialist. These parties work very closely together in the execution of all actions in a universal

Blast Plan for the project to ensure that marine species are protected during underwater blastingactivities. An example of such a program and how it was executed is described by Jordan et al(2007) in a paper titled Port of Miami Project Protecting Marine Species during UnderwaterBlasting. The schematic below from this paper shows the Danger Zone, Safety Zone andWatch Zone as determined and implemented for this specific project.

Figure 5-5: Monitoring Zones for Underwater Blasting Program for Miami Harbor DeepeningProject (Jordan et al, 2007)

An example of some of the elements of a Marine Mammal Watch Plan is shown inAddendum D. This Addendum is not meant to be a comprehensive plan and is only shown asan example of some of the considerations during incorporation of such a plan into the universalBlast Plan.


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5.4 RELEVANT PAST MARINE CONSTRUCTION PROJECTS

Marine construction projects often require the removal and excavation of subsurface rockmaterials. Contract Drilling & Blasting LLC was the drilling, blasting and vibration controlspecialist on several of these projects along the east coast of North America in recent years.Some of these projects with relevance to the Port Everglades Inlet Sand Bypass project are

briefly discussed in the paragraphs below.5.4.1 Port of New York / New Jersey

Deepening of the Port of New York / New Jersey from its original depth of only 17 ft to it presentdepth of 50 ft in some areas, has been ongoing since the late 1800s. From 1999 to 2004 theU.S. Army Corps of Engineers (Corps) completed deepening of the Kill Van Kull and NewarkBay Channels from 40 to 45 feet. With the 45-foot deepening in place, the deepening of the

Ambrose, Anchorage, Kill Van Kull, Newark Bay, Arthur Kill, Port Jersey and Bay Ridgechannels to 50 feet began in 2005 and will continue for several years.

During the deepening of the Kill van Kull channel between Bayonne, New Jersey and StatenIsland, New York, pre-treatment of subsurface rock was required in preparation for dredging.Controlled drilling and blasting was selected as the preferred method of rock pre-treatment,

even in close proximity to residential and commercial structures and to the Bayonne Bridge (thesecond largest steel-span bridge in the United States). Several ship wrecks and other historicalstructures were within the Vibration Impact Distance of 1,500 ft. The aerial picture below showsthe Vibration Impact Distance for a section of this project.

Figure 5-6: Sample Vibration Impact Distance - Port of NY/NJ


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The project was successfully completed and mitigation techniques controlling the impact ofconstruction and blasting activities on the public, surrounding structures and vessel traffic in thechannel proved to be successful.

5.4.2 Miami Harbor, Florida

The Port of Miami is the largest container port in Florida and also handles almost 4 million

cruise passengers annually. In 1990, Congress authorized Phase I and Phase II of thedeepening and expansion of the Port of Miami to meet the growing demands of the commercialand passenger shipping industries. The Water Resources Development Act (WRDA) approvedby Congress at the end of 2007 authorized the Miami Harbor Phase III Dredging Project todeepen the South Channel from its current -42 feet depth to -50 feet.

Phase I of the harbor deepening project was completed in 1993. Phase II was attemptedunsuccessfully in 1994 by a dredging contractor and again by its bonding company in 1999. Theproject was abandoned in 1999 with a significant amount of work uncompleted. In 2000 the Portof Miami approached the US Army Corps of Engineers to finish the project. It was eventuallycompleted in 2006. Phase III of the deepening project has not yet commenced.

During the initial endeavor to execute Phase II, dredging without blasting proved to be

unsuccessful. The typical material section was a foot of silty clay overburden, several feet thecompetent limestone over low strength marl. The contractor attempted to use punching as apre-treatment technique but failed, primarily due to the hard limestone bedrock. The successfulexecution of Phase II in 2005 and 2006 implemented a controlled drilling and blasting programto fragment and loosen the subsurface rock in preparation for dredging.

An aerial picture of the project area with an overlay of the Vibration Impact Distance of 1,500 ftis shown in the picture below.

Figure 5-7: Sample Vibration Impact Distance - Miami Harbor


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Initially, there were many concerns by environmental resource agencies and non-governmentagencies about the use of blasting as a construction technique. However, the use of confinedblasting as a special controlled blasting technique, in combination with several environmentalcontrol and mitigation measures, were successfully utilized to address these concerns. Theproject was completed ahead of schedule and the contractor received an Outstanding Ratingfrom the US Army Corps of Engineers.

The mitigation procedures included a Blast Plan to ensure safe execution of the drilling andblasting program and to protect vessel traffic in the channels, a Vibration Control Program toprotect private citizens and structures in close proximity to the project area and a program toprotect marine life species from construction activities. The area is home to several protected,threatened and endangered species, including the Florida manatee, five sea turtle species,

American crocodile and bottlenose dolphin, in addition to important recreational and commercialfish species. As a result of a successful Protected Marine Species Watch Plan implemented onblast days, there were no injuries of any kind to marine mammals resulting from the blastingprogram.

5.4.3 San Juan Harbor, Puerto Rico

Phase II of the harbor deepening project in San Juan, Puerto Rico, encompassed deepening of

the entrance Bar Channel and interior channels of the harbor with offshore disposal of materials.The project was executed utilizing a combination of drilling, blasting and cutter suction dredgingin exposed sea conditions with rock strengths ranging from 1,500 to 24,000 psi.

The aerial picture below shows a sample Vibration Impact Distance around a section of thisproject, overlapping the two critical structures.

Figure 5-8: Sample Vibration Impact Distance - San Juan Harbor


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Guarding the entrance to the San Juan Bay is the World Heritage site of Castillo de San Felipedel Morro, built in the late 1500s. On the opposite side of the bay, a smaller fort known as ElCauelo complemented the fort's defense of the entrance to the bay. These two historicstructures were less than 1,500 ft away from parts of the project where drilling and blasting wasused for pre-treatment of hard subsurface materials. A well-executed and controlled drilling,blasting and vibration control program ensured protection of these structures from possible

impact from the project.


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Sec t ion 6 - C O N C E P T D R I L L I N G & B L A S T I N G P R O G R A M

In order to develop a Blast Plan for full-scale excavation purposes, a Test Blast Program will beexecuted at the furthest point away from any land-based structures, in order to calibrate the

environment for potential impacts such as ground vibration. From this site-specific calibration, aplan will be developed for blasting increasingly closer to these structures and still remain withinthe allowable vibration and air overpressure limits. The suggested approximate location of theTest Blast area is shown in the aerial picture below.

Figure 6-1: Proposed Area for Test Blast Program

It is not know at this time what the allowed vibration levels at the closest structures to the projectarea would be. As discussed before, the industry standard for residential structures is 2.0 ipsand is based on the USBM guidelines. However, local authorities sometimes have morerestrictive requirements. As an example, the USACE specifies a vibration limit of 1.0 ips for thedeepening project of the Port of New York / New Jersey. The state of Florida has a limit of 2.0for mining projects. It is our understanding that Broward County sometimes imposes a vibrationlimit of 0.5 ips for construction projects in upland areas. It will be important to determine whatrestrictions Broward County would impose of the planned sand trap construction prior toinitiation of a detailed blasting plan.


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It is noted that for a vibration limit of 2.0 ips (which is below the limit for the onset of cosmeticdamage to existing structures), blasting can be performed even at the closest point of the sandtrap area to any structure, without any limitations on design. However, if a vibration limit of 0.5ips is set for this project, the efficiency of a drilling and blasting program for the construction ofthe sand trap would be severely limited, especially in the areas closest to the Points of Americastowers.

6.1 DESIGN OF TEST BLAST PROGRAM

The design of the Test Blast Program will be based on the predictive model for blast inducedground vibration, as described in Addendum C. In the absence of site specific information onattenuation of ground vibration, the generic values for the constants and from the USBMstudies will be used to design the first test blast. That approach would allow a typical blastpattern required to effectively fracture rock of the type expected in the sediment trap area, to beinitiated and for ground vibrations at the closest structure (approximately 1,027 ft away) to bewell below a level that could cause any damage to the structure.

Assuming that the vibration data collected from the Miami Harbor Deepening project isrepresentative also of anticipated vibration readings for blasting of rock in Port Everglades, thesite specific constants as calculated in Addendum C can also be used to design the first testblast. Utilizing the methodology described in Addendum C to estimate blast induced groundvibration, and assuming the Miami values for the site specific constants and , a maximumexplosives charge length of 15 to 20 ft can be detonated for the anticipated vibration at theclosest structure to remain below 0.5 ips. This approach has been verified by also consideringthe site specific constants calculated from many years of blasting in the Port of New York / NewJersey.

The table below shows the maximum amount of explosives that can be fired per delay at thetest blast location without exceeding a given vibration level, utilizing the site specific constantscalculated from Miami Harbor blasting data and from NY/NJ blasting data. Even the lowestquantity of explosives per delay in the table above would result in effective fragmentation of the

rock in the test blast program.

Site Specific Constants 2.0 1.0 0.5

USBM Formula 4,408 1,853 779

Miami 1,781 470 124

New York / New Jersey 1,710 554 179

Table 1: Maximum lbs/delay for Given Vibration Limits

6.2 PRODUCTION BLAST PLANThe vibration data gathered during the Test Blast Program will then be used to calibrate theenvironment and calculate the site specific constants for the Port Everglades Inlet. Based onthese new constants and the same model for predicting ground vibration, a Production BlastPlan will be developed. This Plan will ensure that ground vibration and air blast overpressureremains below the allowable limits at the structures within the potential impact zone, but alsothat rock fragmentation is sufficient to allow efficient dredging of the pre-treated material.


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Sec t ion 7 - C O N C L U S I O N S

It is estimated that as much as 280,000 cubic yard of rock may have to be removed for theconstruction of the sediment trap in the Port Everglades Sand Bypass project. It is generally

understood that rock stronger than 6,000 psi cannot be economically dredged without pre-treatment of the material. The largest equipment available in the North American market canefficiently dredge material up tot 4,000 psi in strength without pre-treatment. However, for mostof the dredging equipment, rock stronger than 2,000 psi will have to be pre-treated to enableefficient dredging of the seafloor. Core boring data presently available indicates that most of therock found below -30 feet MLW (-32 feet NAVD) will require pre-treatment.

Drilling and blasting of the bedrock is the most economical and most efficient pre-treatmentmethod. Controlled blasting techniques can be used to accurately create the desireddimensions of the proposed sand trap and at the same time limit any potential adverse impacton the immediate environment by the blasting activities.


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Sec t ion 8 - A D D I T I O N A L W O R K

Planning and design of a specific rock pre-treatment plan, specifically a plan that will includedrilling and blasting, for the proposed Port Everglades Sand Bypass sand trap would benefit

from additional site data collection and analyses. The integration of the excavation methods,potential pre-treatment methods such as submarine blasting, and mitigation for potential effectsof pre-treatment methods will play an essential role in finding the optimal solution forconstruction of the sediment trap at the Port Everglades Inlet.

Accordingly, additional core samples in the proposed sand trap area would facilitate a moreaccurate estimation of the quantity of rock to be removed during construction and the rockquality and hardness. It is recommended that additional rock core samples be collected from thearea closest to the existing structures, on the western side of the sand trap area. Three or fouradditional cores strategically located will be essential in designing an efficient blasting programin this area. Additional samples in the eastern part of the proposed location of the sand trapwould also be beneficial in better defining the sub-ocean conditions at that location which wouldimprove the understanding of the the most optimal dredging and pre-treatment techniques.

The Test Blast program as discussed in Section 5, utilized as input parameters the vibrationconstants as determined in the Port of Miami or the theoretical vibration constants. Theseassumed input data points allow for an estimate of the anticipated vibration levels for the PortEverglades project. However, since vibration control will be such an important factor in thesuccessful execution of this project, it is suggested that a more accurate assessment of the sitespecific attenuation of vibration is done in the Port Everglades Inlet. This can be accomplishedutilizing a special technique called Signature Hole Analysis to pre-calibrate the environmentand estimate the blast design and vibration induced by blasting more accurately.

It is therefore recommended that a signature hole analysis should be conducted to assist incalibrating the environment for vibration, prior to the start of detailed blast design. This type ofstudy can be conducted with relative ease, but requires a specialist in blasting and vibration

control to execute the project.

An essential element in the design of the blasting program is the vibration limits which will beimposed on the project. It is therefore strongly recommended that the consultant for the projectengage with local authorities on this subject and determine the vibration limits that will be placedupon the project, prior to the start of detailed design.

Additional information about the air conditions wells at the Points of America towers should becollected to enable sufficient protection of those structures to blast induced vibration.


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Sec t ion 9 - L I M I T A T I O N S O F R E P O R T

This report is based on our interpretation of the site conditions and other reports as it relates tothis project, our analyses and experience with similar projects. The scope of work was limited to

a review on the preferred method of rock excavation for the construction of the sand bypass atPort Everglades Inlet. We did not review the adequacy of the proposed project and its design, orthe impact that the project may have on its surroundings.

The review was conducted with our best effort in analyzing the available information on theproject and this information with the thoroughness and competence expected of a specialist inthe field.

The report is intended for the use by Olsen Associates, Inc. and Broward County, Florida.


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A D D E N D U M A - R E F E R E N C E S

D2E Report: Assessment of Potential Construction Impacts to Adjacent Structures,Proposed Sand Bypass Project, Port Everglades, Fort Lauderdale, Florida(2007)

Construction Mining Operations Question and Answers Brochure, Office of Florida StateFire Marshall

Siskind, D.E. et al, Structure Response and Damage Produced by Ground VibrationFrom Surface Mine Blasting, OSMRE Report of Investigations 8507 (1980)

Jordan, T.L. et al, Port of Miami Project Protecting Marine Species during UnderwaterBlasting, The Journal of Explosives Engineering, Vol. 24 No. 3 (May/June 2007)

Jordan, T.L. at al, Dodge-Lummus Island Turning Basin Project Protecting Dolphinsand Manatees during Underwater Blasting, 15th Biennial Conference on Marine MammalBiology (2003)

Hempen, G.L. at el, Underwater Blast Pressures from a Confined Rock Removal During

the Miami Harbor Deepening Project, International Society of Explosives EngineersConference (2007)


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A D D E N D U M B - C O N T R A C T D R I L L I N G & B L A S T I N G : P A R T I A LP R O J E C T L I S T I N G

Atlantic Dry Dock: Boat Launch (Jacksonville, FL)

Atlantic Dry Dock: Rock Removal for Navy Dry Dock (Jacksonville, FL)

Bean Stuyvesant: Kill van Kull and Newark Bay Channels, Phase VII (Newark, NJ and NewYork, NY)

Bean Stuyvesant: Kill Van Kull Expansion - KVK Contract 1 (Newark, NJ and New York, NY)

Bean Stuyvesant: SKVK2 Newark Bay Channel 50ft Project (Newark, NJ and New York, NY)

Bean Stuyvesant: KVK Contract 7 (Newark, NJ and New York, NY)

Bean Stuyvesant/Great Lakes Dredge & Dock JV: Kill Van Kull and Newark Bay Channels,Phase V (Newark, NJ and New York, NY)

Don Jon Marine: Arthur Kill Contract 1, Newark (NJ and New York, NY)

Great Lakes Dredge & Dock Company: Castaway Cay (Abaco, Bahamas)

Great Lakes Dredge & Dock Company: Channel Improvements KVK-4A, NY/NJ Harbors(Newark, NJ and New York, NY)

Great Lakes Dredge & Dock Company: GBS Float Out and Towing Channels (Hibernia,Newfoundland)

Great Lakes Dredge & Dock Company: Portsmouth Port Authority Expansion (Portsmouth, NH)

Great Lakes Dredge & Dock Company: San Juan Harbor Deepening Project Phase II (SanJuan, Puerto Rico)

Great Lakes Dredge & Dock Company: Wilmington Harbor (Wilmington, NC)

Great Lakes Dredge & Dock Company: Arthur Kill Channel Navigational Improvement Project(Newark, NJ and New York, NY)

Great Lakes Dredge & Dock Company: Miami Harbor Blasting Project (Miami, FL)

Great Lakes Dredge & Dock Company: Newark Bay Channels Navigation Improvement Project(Newark, NJ)

Great Lakes Dredge & Dock Company: KVK4C (Newark, NJ and New York, NY)

LTI, Inc.: Wilmington Harbor Blasting (Wilmington, NC)

Misener Marine: Freeport Container Port (Freeport, Grand Bahamas)

Misener Marine: Port Manatee Navigation Improvement (Port Manatee, FL)

Project Consulting Services: Hubline Pipeline Project (Boston, MA)

URS Corp: NY/NJ Harbor 50' Channel (Newark, NJ and New York, NY)

USACOE: Wilmington Test Blast Mitigation (Wilmington, NC)

Weeks Marine: (USACOE) Channel Improvements (Wilmington, NC)

Weeks Marine: Channel Improvements KVK4B (Bayonne, NJ)

Woodward-Clyde, Arthur Kill/KVK Blasting Impact Study, NY/NJ Harbors


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A D D E N D U M C - S I T E S P E C I F I C V I B R A T I O N C O N S T A N T S( M I A M I H A R B O R D E E P E N I N G P R O J E C T )

Vibration data collected during the Miami Harbor Deepening Project was used to calibrate the

environment for that specific project. The standard formula for calculating peak particle velocityis discussed below and the calculation of the site specific constants and is shown.

(a) Methodology

The standard formula for calculating Peak Particle Velocity (PPV) is:

=

w

dppv

Equation 1: General form for calculating PPV

where is a coefficient that is determined by the rock quality, and is the decay factor of thevibration waves. The quantity

w

d

is commonly referred to as the scaled distance, where d is the known distance from the blastsite to a specified location, and w is the charge weight per 8 millisecond delay interval. Thecoefficient can range from 50 to 500 with variables in imperial units. The decay factor, whichis always negative, usually ranges between -1.0 and -2.0, but is typically on the order of about-0.2 to -1.6, depending on the specific geology.

The formula to calculate weight when the distance and peak particle velocity are known, is:

2

1

=

ppv

dw

Equation 2: General form of PPV formula solved for Charge Weight

(b) Calibration of the Environment

A calibration of the environment was performed in the Miami Harbor using Instantel Blastmate IIIor Minimate seismographs to simultaneously measure blast induced ground vibration and air

overpressure at different distances from the blast area. This enables the Seismic Specialist tocalculate the ground constant and decay factor for the specific environment in which blasting isconducted.

The picture below shows a Blasmate III set up with a microphone for measuring air blastoverpressure and a geophone for triaxial measurement of ground vibration.


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Figure 9-1: Instantel Blastmate III Seismograph

The data in the table below was obtained in June/July 2005 from blasting performed over anextended period of time in Miami Harbor from the Apache drill boat.

Table 2: Sample Seismic Data Set from Submarine Blasting in Miami Harbor

The seismographs measure the maximum displacement in the transverse, vertical, andlongitudinal directions (Cartesian coordinate system) during a particular event. The highestdisplacement in any one of the directions at any point in time during the recorded event isreported as the Peak Particle Velocity (PPV). This is the figure that is typically reported fromblast induced vibrations.


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Sometimes the quadrature of the component vectors is calculated at every sample interval andthe maximum value is reported as the Peak Vector Sum (PVS). The PVS is always larger thanany one of its x, y, or z component vector constituents since it is representing all three values. Aregression analysis performed on the PVS versus scaled distance will therefore result in aconservative formula for forecasting maximum displacement.

However, the standard technique is to perform a regression analysis on PPV, resulting from ablasting event with a known quantity of explosives per delay and PPV measured at a knowndistance away from the blast zone. A regression is therefore performed on PPV versus scaleddistance and the results can also be reported in equation form.

Figure 9-2: Regression Analysis Performed on Miami Harbor Data

In the above data set collected during blasting in Miami Harbor, the coefficient wasdetermined to be 55.3 with a decay factor equal to -1.04. This is a good representation ofthe actual vibration history, because data from all 14 test blasts were used in the regressionanalysis. Using the constants determined from the above regression and Equation 2, weight canbe solved at any given distance for a particular PPV value. A sample tabulation of maximumallowed weight of explosives per delay at a given distance away from the blast area is shown inthe chart below.


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Figure 9-3: Charge Weight and Distance

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