FPL_Dam_Safety_and_Construction_Plan-_ADDENDUM_No.1.pdf

DAM SAFETY AND CONSTRUCTION PLAN

SANFORD COOLING POND

City of DeBary Ft. Florida Bridge Replacement

August 2025

Purpose of Dam Safety Plan and Description of Project

The purpose of this plan is to provide monitoring and construction criteria for the safe dewatering, excavation, installation, and backfilling associated with the City of DeBary’s Ft. Florida Bridge Replacement in the vicinity of the spillway discharge structure at the Sanford Plant Cooling Pond.

The jobsite is located approximately 180 feet from the exterior edge of the Cooling Pond’s crest road and emergency spillway structure. Expected excavation depth due to this project is currently unknown at the preparation of this Dam Safety Plan. This proximal distance and depth put the excavation within the high-risk zone that requires a dam safety plan and special procedures. The Cooling Pond stage is currently 24.99 feet NGVD.

Based on the current conditions, location/proximity to the dam, and unknown depths of the required excavations, this work could pose a risk to the Cooling Pond’s earthen dam. This Dam Safety Plan provides requirements on methods and material to protect the dam from the potential risks. The potential risk to the dam is the increased likelihood of piping if the soil is loosened (e.g. due to equipment disturbance or inadequate dewatering or a combination of both) or voids are left unfilled, or the soil backfill material has an improper composition (e.g. debris, organics, or too coarse), or the backfill is inadequately compacted.

This dam safety plan addresses known potential issues with construction near the dam and requires that immediate notifications be made if certain undesirable conditions occur. Prior to the start of construction, the Contractor shall provide the FPL Dam Safety Engineer with a copy of its construction plan to assess whether modifications to this Dam Safety Plan are necessary. To ensure the integrity of the dam and identify and react proactively to potential problems, this plan provides guidance that must be followed. No deviations to this plan are allowed without prior approval by the FPL Site Representative and FPL Dam Safety Engineer. If any changes to the scope of work are made at any point of the project, the FPL Site Representative and FPL Dam Safety Engineer must be informed to assess potential impacts to the safety of the dam.

The Ft. Florida Bridge spans the drainage channel downstream of the Sanford Plant emergency spillway, which carries spillway discharge and stormwater runoff from surrounding lands. The channel must remain clear and unobstructed throughout the bridge replacement project to ensure proper water flow. Per Dam Safety protocols, prior to construction the Contractor must provide a drainage diversion plan to the FPL Site Representative and FPL Dam Safety Engineer. Any water backup in this channel could reach the earthen dam toe and risk dam failure.

All open excavation work with depths greater than 24” must be performed with the water table at or maintained at least one foot below the bottom of the excavation. Any additional necessary excavations (i.e. not expected or not explicitly prescribed in the scope of work) would require dewatering. All dewatering shall be by well points. The well points shall be abandoned by “grouting” as described below. Dewatering ensures that no hydraulic gradient influence will push materials up into the open excavation and potentially initiate a piping failure of the dam. No excavations are to be left open overnight and must be backfilled according to backfill requirements.

Safety of the workers performing the work and the community at large could be at stake if dam safety requirements are ignored.

Jobsite Responsibilities

The supervisors in charge of the work must be familiar with the requirements of this plan as it pertains to them before construction begins. Construction crews must also be familiar with the construction criteria and the red flags, monitoring, and notification provided in Appendix B. The FPL Dam Safety Engineer will participate in a pre-construction meeting to provide an opportunity for the supervisors and construction crew to ask questions or seek clarifications on the Dam Safety Plan.

Dam Safety Criteria

The plan requires that the contractor and the on-site staff know the criteria for 1) dewatering, excavation, backfill, and compaction, 2) the red flag criteria, communication requirements, and required actions.

This plan must be strictly adhered to; failure to follow the dam safety plan can result in dismissal of the person responsible for deviation, significant project delays and high risk to the dam.

All applicable "Red Flag" conditions (Appendix B) shall be monitored for whenever there is an open excavation greater than 24 inches in depth. Should a red flag condition develop, the activities must stop immediately, the appropriate staff including the FPL Dam Safety Engineer shall be contacted per the Dam Safety Communication Protocols, and the countermeasures implemented per the red flag criteria.

The Contractor shall maintain a stockpile of 30 cubic yards of filter sand (meeting specification in Appendix A) and 30 cubic yards of FDOT Number 89 Stone stockpiled in a location adjacent to the job site. The filter sand and 89 stone are available to 1) react to unforeseen conditions (e.g. rainfall, excess seepage, or red flag conditions), 2) facilitate compaction, and 3) make up lost soil.

The following sections provide construction criteria to mitigate risk to the dam.

Dewatering Requirements

The following dewatering procedures are for excavation with a maximum depth of 10 feet. If excavations greater than 10 feet below ground surface are required, the Contractor must inform the FPL Site Representative and the FPL Dam Safety Engineer prior to continuation of work.

The Contractor is required to identify the water depth along the proposed excavation before work is started. The Contractor is allowed to determine the current water table depths by excavation of a small hole using post hole/and auger/shovel to the water table. The borehole shall be filled with clean sand meeting the gradation requirement for filter sand provided in Appendix A and compacted in six-inch lifts. The compaction can be done with the closed end of a pipe or a tamper.

Dewatering must be maintained until the excavation is completely backfilled. The dewatering shall be monitored and staffed 24/7 whenever the excavation is deeper than two feet. Each dewatering pump shall have a backup pump ready to operate. The primary pump and the backup pump shall have the required fittings and valves to change between pumps in less than 30 minutes with minimum staffing.

All dewatering shall be by well points. All dewatering shall be installed at least three days before the excavation is started. The contractor may install an un-pumped well point/monitor well to determine when the water level is low enough.

Well point holes shall be abandoned by tremied cementitious fill (“grouting”) to within two feet of ground surface. The tremie may be through the well point starting as the well point is withdrawn or through a separate pipe extending to the bottom of the well point or the well point may be abandoned in place by filling the well point with cementitious filled tremied from the bottom. After grouting of the well points, the well point remnant will be cut off at 18 to 24 inches below ground surface and filled with filter sand. The cementitious flowable fill may consist of neat cement or a cement bentonite mixture. For neat cement the maximum water to cement ratio is 0.53, or 6 gallons of water per 94 lb.

sack of cement. For cement bentonite mixture the content of bentonite shall not exceed 4% by weight and shall have a density of at least 9.4 pounds per gallon. The bentonite shall be at least 85 percent montmorillonite and meet API specifications standard 13A.

The Supplier shall submit a dewatering plan describing the well points depth, screen length, screen depth, screen slot size, and gradation of filter sand if used. The Contractor shall fill any subsidence around the well point of more than six inches with sand meeting the gradation in Appendix A (“Filter Sand”).

Backfilling Requirements

A stockpile of clean Filter Sand (Appendix A) or structural fill (sandy soil free of organic materials) sufficient to fill the excavation will be maintained immediately adjacent to the excavation. If a structural fill is used, the Contractor will provide the gradation specification to the FPL Dam Safety Engineer for review and approval prior to staging onsite. The cuttings/spoils obtained from the excavation may not be used as backfill in any quantity. The equipment necessary to perform the backfilling shall be in the immediate area with an operator immediately available.

The backfill will be compacted to at least 90 percent of the maximum dry density as measured by the Modified Proctor Test (ASTM-1557) in 6-inch lifts. Due to the proximity of the Dam and plant equipment all compaction shall be performed using a vibratory plate compactor. No excavations may be left open overnight until proper backfill requirements are met.

Drainage Diversion Requirements

The Ft. Florida Bridge spans the discharge channel downstream of the Sanford Plant emergency spillway, which carries spillway discharge and stormwater runoff from surrounding lands. The channel must remain clear and unobstructed throughout the bridge replacement project to ensure proper water flow and prevent any hydraulic backup. Per Dam Safety protocols, the Contractor must provide a drainage diversion plan to the FPL Site Representative and FPL Dam Safety Engineer for approval. The plan will be assessed by FPL to ensure adequate drainage pathways are maintained throughout the entirety of the project and water backup onto FPL property will not create additional risk to the dam.

This requirement is critical because any water backup in this channel could reach the toe of the earthen dam, creating hydrostatic pressure that can cause seepage, erosion, and potential slope instability.

Standing water at the dam toe increases pore water pressure within the embankment materials, reducing the effective stress and shear strength of the soil. This condition can lead to foundation weakening, internal erosion (piping), or in worst-case scenarios, catastrophic dam failure. The unimpeded flow of this drainage channel is therefore essential to maintaining the structural integrity and safety of the dam throughout construction operations.

Vibration Monitoring Requirements

If any construction methods are required that could create excessive vibration (including but not limited to pile driving, heavy machinery drops, dynamic compaction, etc), then vibration monitoring will be required as it has the potential to impact the integrity of the dam. The vibration monitoring shall be located at the closest portion of the toe of the dam. If excessive vibration is expected, the Contractor will coordinate with the FPL Site Representative for the required access to install the vibration monitoring station. Vehicle accessing the monitoring equipment will travel on either the crest road or toe road.

Driving across or along the drainage swale is prohibited. The vibration limit shall be one inch per second and the monitoring equipment shall provide a real time notification. A warning level of 0.8 inches per second should be used. Construction must stop immediately if the 0.8 inches per second vibration level is exceed, and the FPL Dam Safety Engineer should be notified.

Dam Safety Communication Protocols

During normal conditions the Contractor will coordinate through the FPL Site Representative. During technical exchanges with either FPL Dam Safety Engineer or any other FPL staff, the FPL Site Representative shall be kept informed.

If any signs of distress to the dam (e.g. Red Flag Criteria) or actions (e.g. excessive vibration or loads) which would increase the risk to the dam are observed or identified they shall be immediately reported to FPL. The FPL Site Representative (Staff listed in Group 1 of the Emergency Call Down List) will call all of the staff listed in Group 2 of the Emergency Call Down List. If FPL’s Site Representative cannot be contacted, then all of the staff listed in Group 2 of the Emergency Call Down List will be called in the order of the table. The FPL Site Representative or the FPL Dam Safety Engineer (or her designee) shall call the remaining staff on the Emergency Call Down List as appropriate for the conditions. It is recommended that the Cellular Phone Numbers are tried first as each of these staffs are available 24/7 on the Cellular Phones. If directed, the Contractor will call the remaining staff on the call down list.

Emergency Call Down List*

Group 1

FPL Plant Contact Daniel Hall Office: (386) 575-5243 Cell: (689) 352-1549

Group 2

FPL Dam Safety Engineer Natalie Mills Cell: (561) 568-5793

FPL Cooling Pond Manager Eric Ryan Cell: (386) 690-1010

FPL Environmental Lead Daniel Hall Office: (386) 575-5243 Cell: (689) 352-1549

Group 3

FPL Plant Manager Luke Reagan Office: (386) 575-5156 Cell: (470) 309-6899

*The Emergency Call Down List will be updated prior to the start of construction to include the contact information of the Contractor and other key project contacts.

APPENDIX A

FILTER SAND SPECIFICATION

For use at FPL-owned cooling ponds

Filter Sand. Filter sand shall be graded silica sand conforming to the following gradation:

US Standard Sieve Size No.

Percent Passing

¼ 100 8 80-100 30 5-50 50 0-10 100 0-5

Supplier shall submit a gradation curve for the proposed filter sand certified by aggregate supplier’s QC department.

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APPENDIX B

RED FLAG CRITERIA FOR WORKING NEAR A DAM

1.0 SCOPE

This document covers FPL's red flag criteria for construction, drilling, sampling or penetrometer testing operations near the Manatee, Martin, and Sanford Plant’s cooling ponds. The cooling pond dams are considered high hazard facilities due to the potential for significant property damage and loss of life.

The red flag criteria identify conditions that can occur during excavation or subsurface drilling that require rapid identification, notification, and could require timely countermeasures to minimize potential threats to the integrity of their dams. These red flag criteria do not cover every possibility and correspondingly any party working near the dam is encouraged to notify FPL and seek expert guidance from his or her own organization whenever in doubt about the impact of the observed conditions on dam integrity.

2.0 DEFINITIONS OF PROPOSED ACTIVITIES AND CONDITIONS ENCOUNTERED

Red Flag. An observed condition requiring notification, evaluation, and possible rapid countermeasures to preserve dam safety.

Exclusion zone. An established area or depth adjacent to the dam where any excavation or drilling requires review, oversight, and special techniques to ensure dam safety. The exclusion zone varies with distance from pond, and the depth of the work or the magnitude/frequency of vibrations generated. The exclusion zone is defined as the distance required to maintain a 20 to 1 hydrologic gradient from the maximum pond level to the bottom of the excavation. The stages for evaluation of the gradients at Sanford, Manatee, and Martin are listed below:

At Sanford the maximum water level for short term construction should be 25.0 and 26.00 for design changes (normal maximum pool 24.5 feet NGVD).

At Manatee the maximum water level for short term construction should be 66.50 and 68.50 for design changes

(normal maximum pool 66.0 feet NGVD).

At the Martin the maximum water level for short term construction should be 33.67 and 37.00 for design changes

(normal maximum pool of 33.62 feet NGVD for dry season and 32.83 feet NGVD for the wet season)

Piping (Soil Piping). A piping condition exists when uncontrolled seepage exits the soil’s surface, usually at the embankment toe or into an excavation. This seepage can move the finer portions of soil and create a pipe or small tunnel that can progress backward with the risk of ultimately connecting directly to the reservoir. When a hydraulic connection is made with the reservoir, the flow and the pipe diameter can increase quickly, leading to a breach of the embankment. The presence of highly permeable layers such as the shell layer below the Martin cooling pond increases the likelihood of piping as they increase gradients (by collecting water from under the cooling pond and conveying it below the embankment) and have larger pore spaces. The presence of highly permeable layers also makes it possible to have piping at large depths (sub-surface piping) and distances. A sub-surface piping condition is extremely dangerous because visible surface indicators (e.g. boils or wet areas) will not be present until the condition has progressed possibly beyond the point where repair is likely possible.

Construction or Drilling Supervisor. The geotechnical engineer, lead driller, or construction manager with overall responsibility for all on-site activities. The Construction or drilling supervisor is responsible for the safety of the dam and must have the ability to stop work, make notifications, and begin mitigation efforts as needed.

Drilling Records. Drilling records shall include at minimum the following two types of records:

A general description of the drilling, sampling, in-situ testing, and drilling Equipment.

Detailed logs of the activities describing boring location, surface elevation, drilling fluid used, materials encountered, depth of strata changes, water table, loss of drilling fluid, depth of samples, depth of in-situ tests, any unusual problems, etc.

Board of Review. A group of consultants that FPL uses to review major design and repair decisions. FPL will also confer with the Board of Review as conditions warrant during an emergency condition.

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FPL Representative. The FPL employee who is on site and available during all construction activities and is responsible for communicating, coordinating, and responding to dam safety issue. The FPL representative will be trained in dam safety and identifying potential red flag conditions. It is the representative’s responsibility to ensure the safety of the dam by stopping construction activities and beginning mitigation efforts immediately if conditions warrant. It is also the representative’s responsibility to make certain that red flag conditions or other unknown, potentially dangerous conditions are immediately reported to the FPL dam safety engineer and the plant manager.

Dewatering. An activity used to lower the ground water level in a safe manner to allow excavation and construction.

Dewatering can be done a variety of ways including the use of well points, sock drains, chimney drains, and controlled open ditch drainage. Dewatering in the exclusion zone in an uncontrolled manner is not permitted under any circumstance.

3.0 PRIOR TO CONSTRUCTION

Submittals

Geotechnical work. The geotechnical engineer shall submit a detailed drilling plan identifying drilling locations, methods, depths, and procedures. This drilling plan will be reviewed to determine whether the work is located within the exclusion zone. If the work impacts the exclusion zone, the plan shall be reviewed for dam safety considerations.

Civil/Earthwork. Any earthwork in the exclusion zone that requires excavation of greater than 12 inches, changes the flow of drainage water, requires access across or along the embankment side slope or drainage swale, or increases the load on the embankments (or any combination of these) requires detailed plans. Excavations below the water table are not permitted without an approved dam safety plan. If excavations are required below the water table, a detailed dewatering plan must also be submitted demonstrating the ability to reliably dewater to a depth of at least one foot below the deepest planned excavation.

Unauthorized excavations are a red flag and shall be immediately repaired.

Dam Safety Tailboard Meetings The contractor (and any subcontractor performing work in the exclusion zone) is required to attend a dam safety tailboard meeting prior to start of work.

4.0 RED FLAG CRITERIA

Artesian condition

Water flowing out of the ground or an open excavation or bore hole constitutes an artesian condition. This condition is caused when the water pressure (head) in the hole is higher than the ground level. An artesian condition in the exclusion zone represents a dangerous condition. An excavation or bore hole that becomes artesian indicates a serious potential for piping and must be monitored closely and stopped by timely and appropriate methods; especially if the discharge is increasing.

Flow moving fines (e.g. cloudy or silty discharge) indicates the formation of a pipe. This is a very serious condition and could lead to dam failure. Even moderate flows with clear water can change quickly and must be monitored closely and stopped by timely and appropriate methods.

Notification. Immediately notify the FPL site representative, the FPL dam safety engineer, and the supplier’s senior geotechnical engineer.

If artesian conditions are observed the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation and the stage in the cooling pond.

Estimate flow rate and whether flow rate is increasing.

Monitor for cave-in(s).

Monitor for subsidence of the ground surface.

Observe the seepage flow for movement of fine soils from a boil, which is indicative of piping development.

Provide description of activities that lead to the problem.

Take photographs or video clips or both

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The following applicable countermeasures should be implemented immediately:

Counter Measure for Seeps. Construct a berm around the seepage exit area to contain the water and thereby allow the water level to rise until the water level stops rising. If necessary or expedient install a casing that is large enough to encompasses the entire area of seepage. The casing should have sufficient length to embed at least two feet and extend (stickup) at least two feet above ground surface.

Counter Measure for Excavations. Temporarily fill the excavation with filter sand or other material as required to prevent piping of fine sands. If available in the required time frame filter sand should be used to fill the excavation to a depth of at least one foot above the water table. If the side of the excavation are sloughing, the flow into the excavation is increasing or contains fines the excavation should be backfilled with the excavated materials.

Counter Measures for Aerial Seepage. Heap filter sand on area to provide additional resistance to flow and prevent the migration of fine materials as needed. In general, the filter sand should be placed around the perimeter first.

Devices like sand bags may be used to slow/stop water while the interior is filled with filter sand. If the seepage erodes the filter sand quicker than the filter sand can be placed a fine gravel layer may be placed as an intermediate layer. The overlying filter sand should cover the top and all sides of the fine gravel.

Counter Measures for Bore Holes. If the bore hole starts generating water (water level in the mud tub rising) the advancement of the borehole shall be stopped immediately and not proceed until the drilling mud is thickened sufficiently to stop the flow or casing is installed to provide a riser, along with mud thickening, sufficient in height to stop the inflow. If a casing is used it will remain in place until grouting is commenced and grout return is observed, then the casing will be removed slowly while additional grout is added as required to maintain the grout at ground surface. The borehole will be observed for flow and equipment shall be available to set temporary surface casing.

Counter Measures for Other Anomalous Conditions. Seek guidance of the supplier’s Senior Geotechnical engineer and the FPL Dam Safety engineer.

Boils

Boils occur where an artesian condition exist above ground (usually near the toe of the dam), under water, in an excavation, or near construction activities. Boils can form in a relatively short time period and may or may not flow all of the time. Boils are usually identified by a small cone of sand appearing around a hole. If a boil occurs under flowing water, it may be identified by a muddy plume.

Should a new boil be observed near a drilling operation, it is likely that the drilling has changed the subsurface conditions near the borehole.

Notification. Immediately notify the FPL site representative, the FPL dam safety engineer, and the supplier’s senior geotechnical engineer.

If a boil is identified the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, diameter of boil, depth of boil.

Determine the stage in the cooling pond Estimate flow rate and whether flow rate is increasing.

Monitor for cave-in.

Monitor for grade subsidence around bore hole.

Observe the seepage flow for movement of fine soils from the boil, which is indicative of piping development.

Provide drilling logs.

Take photographs/video if possible

The following applicable countermeasures should be implemented immediately:

Construct a berm around the boil to allow water level to rise and resist flow from the boil. If necessary or expedient install a casing that is large enough to encompasses the entire area of seepage. The casing should have sufficient length to embed at least two feet and extend (stickup) at least two feet above ground surface.

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Temporarily fill the boil with filter sand or other material as required to prevent piping of fine sands.

Follow boil repair procedure.

Seek guidance of the supplier’s Senior Geotechnical engineer and FPL Dam Safety engineer, and the Board of Review.

Loss of Drilling Fluid or Loss of Drilling Fluid Circulation

The loss of drilling fluid can be a red flag condition because it indicates the presence of a void or flowing water under the ground surface. Drilling into this condition can create a connection between normally stabile soils and void permitting the creation of a piping situation that goes unnoticed. This can be a serious situation that must be mitigated.

When drilling mud is employed to counter seepage pressures that can exist down a drill hole, loss of circulation for a significant length of time or over a significant vertical height of drill hole should be considered a red flag. Moderate fluid loss would likely indicate the presence of a porous/permeable zone. Total circulation loss could indicate the presence of an immature sink hole.

Notification. Immediately notify the FPL site representative, the FPL dam safety engineer and the supplier’s senior geotechnical engineer.

If circulation loss occurs the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, depth of bore hole, elevation of bore hole bottom.

Monitor for rod drops.

Monitor for cave-in.

Monitor for grade subsidence around bore hole.

Monitor for onset of Artesian condition Estimate loss of circulation, partial or total, and flow volume.

Provide drilling logs

The following applicable countermeasures should be implemented immediately:

Increase or Improve Drilling Fluid. Increase viscosity of the drilling fluid or provide additives to assist in sealing the borehole. An increase in the supply of drilling fluid may be necessary to maintain head pressure.

Case the Borehole. If full circulation cannot be quickly restored or the borehole is showing signs of sloughing install casing.

If casing is not possible or practical, or if a change in drilling fluid is not effective, cease further advancement of the drill hole and seek guidance of the supplier’s Senior Geotechnical engineer and FPL Dam Safety engineer.

If the bore hole or excavation becomes Artesian, follow Artesian countermeasures.

Soft Spots

The unexplained appearance of soft spots at or near construction activities could indicate high pore pressures in an isolated area. This condition may be an indicator of an area with high seepage area. Without mitigation, soft spots must be monitored continuously and investigated as required to ensure that the spots do not turn into boils.

Notification. Immediately notify the FPL site representative, FPL’s dam safety engineer and the supplier’s senior geotechnical engineer.

If soft spots are encountered the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, approximate surface area of soft spot, and the stage in the cooling pond.

Monitor for movement.

Monitor for cave-in.

Monitor for onset of artesian condition Provide detailed description of activities in the general area.

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The following applicable countermeasures should be implemented immediately:

Prevent traffic for going over or near area.

Investigate (e.g. look for flow when all outlets are closed) for leaks Seek guidance of the supplier’s Senior Geotechnical engineer and FPL’s Dam Safety engineer.

Depressions or Sinkholes

Depressions or holes that develop near construction may indicate that the flow of water underground has been changed from activities and is resulting in the loss of soil.

Notification. Immediately notify the FPL site representative, FPL’s dam safety engineer and the supplier’s senior geotechnical engineer.

If depression or sinkholes are encountered the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, depth of sinkhole or depression, and approximate surface area.

Monitor for water flow in or out of the hole.

Monitor for cave-in.

Monitor for grade subsidence around bore hole.

Monitor for onset of Artesian condition Provide detailed description of activities in the general area (e.g. truck traffic, loads, vibration, recent drilling, or recent excavation.

The following applicable countermeasures should be implemented immediately:

Cease all activity in the area.

Move equipment to safe location.

Seek guidance of the supplier’s Senior Geotechnical engineer, the FPL Dam Safety engineer, and the Board of Review.

Cracks, Sloughs, other Movements

Vibrations and variations in soil pore pressures can lead to slope movement. When working near a dam, the slope should be monitored continuously for any kind of movement. Large scale movement may be noticed first as a crack or line in the grass covering the downstream slope. Depressions or humps in the slope may also indicate movement.

Notification. Immediately notify the FPL site representative, FPL’s dam safety engineer and the supplier’s senior geotechnical engineer.

If cracks, sloughs, or other movements are encountered the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, location, and approximate surface area.

Monitor for water flow.

Monitor for cave-in.

Monitor for continued movement, estimate rate or movement.

Monitor for onset of Artesian condition Provide detailed information on the activities in the general area.

The following applicable countermeasures should be implemented immediately:

Cease all activity in the area.

Move equipment to safe location.

Seek guidance of the supplier’s Senior Geotechnical engineer and FPL’s Dam Safety engineer.

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Rod Drops

Large single rod drops or multiple smaller rod drops should be considered a red flag. This most likely would indicate the presence of very loose/soft material and possibly a void or porous zone.

Notification: If a single drop of more than one foot occurs or two or more drops of six inches or more occurs immediately notify the FPL site representative, FPL’s dam safety engineer and the supplier’s senior geotechnical engineer.

If cracks, sloughs, or other movements are encountered the following information should be collected to the extent is does not interfere with implementing countermeasures:

Determine ground elevation, depth of bore hole, elevation bore hole bottom.

Monitor for loss of circulation.

Monitor for cave-in.

Monitor for grade subsidence around bore hole.

Monitor for onset of Artesian condition Estimate loss of circulation, partial or total, and flow volume.

Provide drilling logs

The following applicable countermeasures should be implemented immediately.

Cease further advancement of bore hole and seek guidance of the supplier’s Senior Geotechnical engineer, the FPL

Dam Safety engineer, and the Board of Review. This will normally involve a consensus recommendation.

If the bore hole or excavation becomes Artesian, follow Artesian countermeasures.

Any Unknown or Changing Condition Any condition observed to be unusual or changing should be considered a red flag until it can be determined otherwise.

Notification. If an unknown or unusual condition arises, notify the FPL site representative, FPL’s dam safety engineer and the supplier’s senior geotechnical engineer.

The following applicable countermeasures should be implemented immediately.

Determine ground elevation and location of the condition.

Monitor for continued changes.

Cease construction activities in the area.

Seek guidance of the supplier’s Senior Geotechnical engineer and the FPL Dam Safety engineer.