Attch 3_Dredging Specs 35 20 23.pdf

Maintenance Dredging Portsmouth Naval Shipyard, Kittery, ME

Section 35 20 23 Page 1

SECTION 35 20 23

DREDGING

04/06 (Revised 4/2020)

PART 1 GENERAL

1.1 DEFINITION

Hard material is defined as material requiring blasting or the use of special equipment for removal, and includes large boulders and or fragments too large to be removed in one piece by the dredge plant. Boulders and rock fragments less than 2 tons in weight are not considered hard material. The dredge plant must be capable of removing boulders and rock fragments up to 2 tons in weight.

The dredge plant must also be capable of removing hard material in specified locations without the use of blasting.

1.2 SUBMITTALS

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

submittals not having a "G" designation are for Contractor Quality Control approval. Submit the following in accordance with Section 01 33 00

SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Construction Operations Plan; G

Seawater Intake Turbidity Protection Plan; G

Lobster Mitigation Plan; G

Marine Mammal Monitoring Plan; G

Hydrographic Survey Methods; G

Pre-Final Design; G

Ready for Construction Documents; G

Material Sampling and Testing Plan; G

Method for Computing Quantities; G

Estimated Quantity Calculations; G

SD-02 Shop Drawings

Dewatering Plan; G

Soundings; G

SD-11 Closeout Submittals

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Material Test Results; G

Post-dredge Hydrographic Survey; G

Quantity Calculations; G

Approved Manifest; G

1.3 MATERIAL TO BE REMOVED

The material to be removed is silt, sand, gravel, cobbles, boulders, artificial obstructions and other dredge materials. In specified locations hard material or bedrock will be required to be removed. At Berth 6A and Berth 14 all material, including hard material must be removed to the design dredge depth.

Drawings and historical borings along Berth 6 are provided as attachments 5 and 8 respectively and are included for general information to help the contractor understand soil and rock characteristics and volumes at Berth 6.

This data reflects the material characteristics at that time and shall not be used as a basis of characterization for disposal. Based on this information, it is estimated that approximately 260 CY of bedrock at Berth 6A and 185 CY of bedrock at Berth 14 requires removal under this contract.

Actual quantity of bedrock may be substantially greater or less than these estimations, so it is the responsibility of the contractor to determine their own estimated quantities for bidding purposes. No financial or schedule adjustment will be granted for bedrock quantities above or below any estimated volumes. No removal of hard material is expected or required beyond designated areas of Berth 6A and Berth 14. The contractor is responsible for sampling, testing and characterization of all material for disposal.

1.3.1 Hard Material

The removal of hard material is required for the dredge area in Berth 6A and Berth 14 as shown on the drawings. The rest of the project area does not require the removal of hard material. Should the Government direct in writing that hard material be removed in a location other than Berth 6A and Berth 14, the work shall be performed and an adjustment in the contract price or time for completion, or both, will be made in accordance with "FAR 52.236-2, Differing Site Conditions."

Hard material removal will be accomplished by mechanical means such as drilling, grinding or hammering. Blasting is not permitted on this project.

Mechanical rock removal activities will be limited to approximately 12 hours per day and will implement a “soft-start” to allow for a period of time when sturgeon would be able to pass through the zone of influence without exposure to underwater noise.

If Contractor encounters hard material within the design dredge depths outside of Berth 6A and Berth 14 dredge limits, Contractor shall demonstrate to the Government's satisfaction that the material is not excavatable by the equipment used for this project, and shall identify the limits and elevations of the hard material as directed, at no additional cost to the Government.

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1.4 ARTIFICIAL OBSTRUCTIONS

The Government has knowledge of material, including but not limited to, metal bands, pallets, pieces of broken cable, rope, fire hose, concrete blocks, miscellaneous metal, chain, broken piles, etc. within the area to be dredged. The Government has no knowledge of existing ordnance, wrecks, wreckage, or other material of such size or character as to require the use of explosives or special or additional plant for its safe removal.

Artificial obstructions excavated from the dredged area shall be placed in the dewatering area separate from the dredge materials, and shall be rinsed for review by the Government. All artificial obstructions shall become the property of the Contractor unless otherwise directed or indicated, and shall be properly disposed of at the end of the project at a Government approved facility, at no additional cost to the Government.

1.5 QUANTITY OF MATERIAL

The estimated quantity for bidding purposes and for application of the "FAR 52.212-11, Variation in Estimated Quantity" shall be as shown in the table in section 3.5 and on the drawings. The quantities listed are estimates only. Within the limits of available funds, complete the work specified whether the quantities involved are greater or less than those estimated.

1.6 OVERDEPTH DREDGING

To cover unavoidable inaccuracies with the dredging process, where overdepth dredging is indicated, material actually removed to a depth of 2 foot below the design dredge depth specified and within the dredging limits will be measured and paid for at the bid unit price.

Material excavated below or beyond the limits shown on the drawings will not be measured or included for payment.

1.7 SIDE SLOPES

Dredging on side slopes shall follow, as closely as practicable, the lines indicated or specified. A __2___ foot allowance will be made for dredging beyond the indicated or specified side slopes, except as provided herein.

The amount of material excavated from side slopes will be determined by the approved method for computing dredge quantities.

1.8 PERMIT

The Contracting Officer will secure the permits for dredging and disposal of material as indicated. The Contractor shall comply with conditions and requirements of the following permits, at a minimum. Copies of the permit applications submitted to regulatory agencies are included as attachment 7 and a copy of the final approved permits will be provided once issued.

(1) Army Corps of Engineers General Permit

(2) Maine Department of Environmental Protection Site Location of Development Minor Revision, Natural Resource Protection Act, Coastal Wetland Alteration, and Water Quality Certification.

All listed permits will be in effect through the duration of the project.

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The Contractor shall make arrangements with a Government approved state licensed landfill for disposal of excavated materials.

1.9 CHARGES

The Contractor shall pay all costs associated with the transportation of the dredge materials from the dewatering site to the state licensed landfill, and shall pay all charges required by the landfill for the proper disposal of the dredge material.

The Contractor is responsible for all sampling, testing, segregation and processing of the dredge materials required by the state licensed landfill identified for disposal, as required by the State of Maine Department of Environmental Protection Solid Waste Division, and as required by the state in which the landfill is located. Costs for this work shall be included in the lump sum contract price for the Base Bid, and in the lump sum contract price for Bid Option.

1.10 ENVIRONMENTAL PROTECTION REQUIREMENTS

Provide and maintain during the life of the contract, environmental protective measures. Provide environmental protective measures required to correct conditions, such as oil spills or sediment releases beyond de-mimimus quantities that occur during the dredging operations. Comply with Federal, State, and local regulations pertaining to water, air, erosion and sediment control, and noise pollution. Comply with permits applicable to the work. Turbidity curtains will be used where water velocities and dredge depths make their use practicable.

Comply with the Dredging Permits, which require that dredged material be dewatered on the barge scow and amended with cement to solidify the material before transportation for disposal. The Permits also require that a containment area be installed on the barge using concrete barriers wrapped with geotextile fabric. The dredge bucket will deposit the dredged materials within the containment area on the barge. The geotextile fabric must filter the dredged material prior to its decanting into the river. Refer to the Permits for further details and requirements.

Provide erosion and sediment controls at the offload area to minimize point source pollution in accordance with Section 01 57 19.00 22.

1.11 BASIS FOR BIDS

Payment will be at the contract unit price per cubic yard, multiplied by total cubic yards of acceptable dredging. Base bids on total cubic yards of dredging indicated. Include a bid unit price per cubic yard of dredging based on the quantity as specified or indicated. If the Contracting Officer requires an increase or a decrease in total volume of dredging, the contract price will be adjusted in accordance with the "FAR 52.211-18, Variation in Estimated Quantity." Dredging conditions specified and indicated describe conditions which are known. However, the Contractor is responsible for other conditions encountered which are not unusual when compared to conditions recognized in the dredging business as usual in dredging activities such as those required under this contract.

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1.12 CONSTRUCTION OPERATIONS PLAN

Submit a Construction Operations Plan indicating the proposed method by which the dredge work will be conducted. Describe in detail the means by which dredge operations will be conducted so as to avoid damage to benthic resources outside the dredge area. The plan shall include discussion of the following items:

a) Type of dredge equipment and vessels to be used throughout the project,

b) Coordination and communication efforts between site personnel to minimize impact to Portsmouth Naval Shipyard operations,

c) Maintaining horizontal and vertical survey control,

d) Proposed means to avoid damage to adjacent structures, vessels, and moorings, and fenders

e) Proposed means to avoid over dredging,

f) Proposed methods to effectively dewater and remove all dredge spoils from the dewatering site within the project time limits,

h) Proposed methods to keep unloading site and all haul routes clean, and

i) Proposed methods to prevent spillage from trucks.

1.13 SEAWATER INTAKE TURBIDITY PROTECTION PLAN

Submit a Seawater Intake Turbidity Protection Plan which will include shop drawings detailing how the seawater intakes located at Berth 5 (Base Bid) and Berth 14 (Bid Option 1) will be protected from turbidity. In addition to the shop drawings, material specifications will be provided. Approximate examples showing minimum level of effort are provided in the drawing set for reference. The government reserves the right to have the contractor verify the function of the turbidity protection by video, divers, or any means necessary upon request.

1.14 LOBSTER MITIGATION PLAN

Submit a Lobster Mitigation Plan which complies with the requirements and references indicated in Part 3, paragraph entitled "Lobster Mitigation".

Lobster Mitigation activities shall comply with all applicable MEDEP permits.

1.15 MARINE MAMMAL MONITORING PLAN

Submit a Marine Mammal Monitoring Plan which complies with the requirements and references indicated in Part 3, paragraph entitled "Marine Mammal Monitoring".

1.16 DEWATERING PLAN

Submit a Dewatering Plan for the dredge spoils. Dewatering operations shall be conducted on the Contractor’s waterborne plant, no land based dewatering site will be provided as part of this contract. The plan shall indicate the steps and methods the Contractor will utilize to ensure the dredge materials are dewatered sufficiently to allow transport and disposal at a licensed solid waste facility within the

Section 35 20 23 Page 6 specified contract completion date. The Dewatering Plan shall indicate the means and methods for prevention of release of amended dredge spoils from entering the river, and for meeting the requirements for transportation of the dredge spoils to be liquid free prior to transport. Dredge spoils ready for transport shall contain no free draining liquids. When there is a question as to whether this standard is met, as determined by the Government, the Paint Filter Liquids Test (EPA SWA-846 Test Method 9095) shall be used to determine the presence of free draining liquids in a representative sample. The plan must be stamped and signed by a licensed registered Professional Engineer.

1.17 LAYOUT WORK AND SURVEYS

The Contractor shall employ a licensed surveyor to layout the limits of the work, establish vertical control using approved datums and perform surveys. The Contractor shall provide all buoys, ranges and other controls necessary to accomplish the work and facilitate inspection.

1.18 HYDROGRAPHIC SURVEYS

The contractor shall submit pre-dredge and post-dredge hydrographic surveys and quantity calculations. Prior to commencing work, submit hydrographic survey methods to the Contracting Officer’s Representative. Hydrographic surveys shall use multi-beam sonar transducers and shall provide 100% bottom coverage including a method to correct for side slope and beam angle error.

Survey methodology shall conform to the US Army Corps of Engineers specification EM1110-2-1003, as amended. Survey accuracy shall be as follows: horizontal positioning: less than 1 meter; NADIR (vertical): ±0.15 feet. Plans for the Hydrographic Surveys shall include a typical section of the proposed dredge areas.

1.18.1 DELIVERABLES SCHEDULE

Provide the following design and close-out deliverables in digital ACAD format (2016 or earlier version) and stamped/signed PDF for each deliverable. Approved Post Dredge Survey shall be stamped and submitted on mylar.

i) Pre-Final Design deliverable showing hydrographic conditions from KTRs pre-dredge survey, final grading design, and estimated quantity calculations.

ii) Ready for Construction Documents, incorporating comments from review of Pre-Final.

iii) Post Dredge Survey and Quantity Calculations

All pre- and post-dredge surveys and drawings shall be prepared in accordance with CAD Standards included as attachment to Section 01 78 00.00 22.

[Pre-dredge surveys are required to be performed within 30 days for each location to be dredged. Surveys for bid options areas, if awarded, are to be concurrent with base bid phasing as described in Section 35 20 23, Paragraph entitled "Order of Work".

[The above described submittal requirements does not relieve the contractor from conducting interim surveys during construction as described in Section

Section 35 20 23 Page 7

35 20 23, paragraph entitled "Surveys During Progress of Work".(Amendment 0001, RFI 11 Response)].

1.19 METHOD FOR COMPUTING QUANTITIES

Submit Method for Computing Quantities. Method must be a generally recognized technique using TIN subtraction method of calculation and must be compatible with AutoCAD Civil 3D 2018 software.

1.20 MATERIAL SAMPLING AND TESTING (BASE BID)

1.20.1 Material Sampling and Testing Plan

Contractor shall conduct additional sampling of the dewatered dredge spoils as required for disposal of the materials in accordance with state and licensed landfill requirements. Submit a Material Sampling and Testing Plan.

Contractor shall ensure that a sufficient quantity of samples and tests are performed to meet the state and licensed landfill requirements for acceptance of the material for disposal. The plan shall include sample frequency, sampling methods, compositing methods, testing parameters, detection limits and quality assurance requirements.

1.20.2 Dredge Material Sampling

Samples of the dredge material shall be collected in accordance with the approved Material Sampling and Testing Plan (Base Bid). Sampling will be in accordance with standard reference procedures from the US Army Corp of Engineers, the State of Maine Department of Environmental Protection Solid Waste Division and the Environmental Protection Agency's publication SW-846, "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods".

1.20.3 Dredge Material Testing

Testing of the dredge material will be in accordance with the approved material sampling and testing plan, the State of Maine Department of Environmental Protection Solid Waste Division, the approved state licensed landfill, and the state in which it is located. Submit Material Test Results. Sediment free rock does not need to be tested, nor is considered waste as outlined by the Maine Department of Environmental Protection.

1.21 POST-DREDGE HYDROGRAPHIC SURVEY

Submit a Post-dredge Hydrographic Survey and Quantity Calculations. Survey methods shall be in accordance with approved methods designated herein. Electronic hydrographic surveys shall be submitted in AutoCAD Civil 3D 2016 format. Drawings shall be drawn at 1 foot contour intervals on 22"x34" size mylar showing the full length of all piers, berths and dry docks where dredging was accomplished. Plans and quantity calculations shall be stamped and signed by a licensed registered Professional Engineer. Xyz files of the survey data must be submitted for all post dredge surveys.

1.22 MATERIALS TRANSPORTATION

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Contractor shall transport materials from barge to Building 357, and from building 357 to approved disposal facility, as indicated. All land transportation shall be conducted in watertight trucks to avoid spillage of dredge spoils before and after dewatering. Contractor shall transport dredge spoils from the dewatering site to the designated location at PNSY for manifesting (Building 357) before proceeding to the disposal facility.

Contractor shall obtain and submit for each accepted delivery to the disposal facility an Approved Manifest. The Contractor shall confirm the operating hours of Building 357 and coordinate transportation of dewatered dredge spoils with Building 357 personnel. All materials shall be transported on the Shipyard between the hours of 8:00AM and 2:30PM Monday through Friday. The allowable trucking routes on the Shipyard are shown on project drawings. Deviation from this Materials Transportation requirements will only be allowed with written permission from the government to utilize a different approved Materials Transportation Plan.

1.23 WORK AREA

1.23.1 PROTECTION OF EXISTING WATERWAYS AND SHOALS

The Contractor shall conduct his operations in such a manner that the material is not pushed outside of dredging limits or otherwise deposited in existing side channels, basins, docking areas, or other areas being utilized by vessels or moored boats. The Contractor will be required to change his method of operations to comply with the above requirements. Should any bottom material or other dredged material be pushed into areas described above as a result of the Contractor's operations, the material must be promptly removed.

1.23.2 ADJACENT PROPERTY AND STRUCTURES

The Contractor shall conduct the dredging operation such that it does not undermine, weaken, or otherwise impair existing structures located in or near the areas to be dredged. The Contractor shall plan the dredge work accordingly. Areas within 10 feet of an existing structure will not be dredged.

Damage to private or public property or structures resulting from the disposal or dredging operations shall be repaired promptly by the Contractor at his expense. Damage to structures resulting from the Contractor's negligence will require prompt repair at the Contractor's expense.

Contractor shall pay special attention to the unloading site and haul routes on Portsmouth Naval Shipyard. Contractor shall employ tailgate locks on trucks or other approved methods to ensure sealing against spillage. Contractor may be required to clean Portsmouth Naval Shipyard haul routes as directed, if the trucks do not prevent spillage of the dredge spoils and water to the satisfaction of the Contracting Officer’s Representative.

PART 2 PRODUCTS

Not used.

PART 3 EXECUTION

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3.1 LOBSTER MITIGATION

Contractor shall carry out lobster mitigation in accordance with the requirements of the permits and these specifications. The complete requirements for lobster mitigation are presented the document titled “Portsmouth Naval Shipyard, Lobster Mitigation Plan, Modification and Expansion of Dry Dock 1” prepared by Stantec Consulting Services, Inc. dated October 25, 2018 included herein as part of the regulatory permit application included as attachment 7 in this bid package.

The contractor shall employ the services of a qualified professional to manage/perform all phases of the lobster mitigation effort. The qualified professional shall be familiar with the Maine Department of Marine Resources requirements, protocols and procedures related to lobster mitigation, trapping, and transport. The person(s) performing trapping activities must be properly licensed in the State of Maine for all activities associated with the lobster mitigation efforts. Submit all reports and data for Government review and acceptance prior to start of dredge operations.

The need for lobster mitigation prior to dredging activities will be determined by the river bottom water temperature within the dredging area.

When the river bottom water temperature is less than 5°C (typically January through late March), no lobster mitigation efforts will be required. When the temperature is above 5°C, lobster mitigation will be required.

The objective of the lobster mitigation is to trap and relocate lobsters in the project area until a threshold, as measured by catch per unit effort (CPUE), of 0.5 lobsters/trap/night set is achieved.

Trapping will target both legal and sub‐legal size lobsters. Legal lobsters typically are retained by the fisherman assisting with the mitigation effort. Sub‐legal lobsters will be transferred to the cove just north of the causeway linking Clark Island to Seavey Island off of the southeast side of Seavey Island. Based on the above water temperature criteria, lobster mitigation, including trapping and relocation of lobsters, will be completed no more than 14 days prior to the start of project dredging. If dredging has not commenced within 14 days of lobster relocation, the mitigation will be repeated to meet the requirement of dredging within 14 days of completion of mitigation.

The contractor shall provide the necessary notifications to the Shipyard regarding the in-water work including the following information:

• Copies of the MDMR Special License;

• Coordination for lobster mitigation plan approval and lobster relocation oversight;

• Logistical considerations for site access and working in secure areas/during simultaneous;

• Routine notification of daily sampling activities and general project progress.

3.2 MARINE MAMMAL MONITORING

Contractor shall submit a Marine Mammal Monitoring Plan in accordance with Attachment 6, Marine Mammal Monitoring Methodology. This plan must be approved prior to any dredging activities. This requirement is only

Section 35 20 23 Page 10 applicable to the Base Bid (Berth 6) and Bid Option 1 (Berth 14) for the duration of rock removal activities. The contractor is responsible for all persons, costs and materials necessary to fulfill the requirements in Attachment 2 and the Marine Mammal Monitoring Plan. Rock removal must immediately stop if a marine mammal approaches/enters the shutdown zones identified in Attachment 6. The shutdown area must be clear of marine mammals or sea turtles for at least 20 minutes before rock removal can begin. Attachment 6 should be carefully reviewed and contains all information regarding Marine Mammal Monitoring and impacts to the project.

3.3 STURGEON AND SALMON MONITORING

The contractor shall provide all labor and personnel required to monitor dredging activity for entrapment/ensnarement of Atlantic and/or short-nosed sturgeon species, as well as Atlantic salmon. A monitor shall be present at all times while dredging is ongoing. The monitor shall be positioned in a location where dredge spoils can be easily observed. If any of the species of concern become entrapped/ensnared in dredge bucket or spoils, all work shall cease, the fish shall be immediately released back to the river, and the NAVFAC PWD-ME Natural Resource Manager (NRM) shall be contacted. Work shall not commence until the NRM receives written concurrence from the National Marine Fisheries Service. The contractor shall meet with the NRM prior to execution of dredge work for fish species identification, handling, and documentation guidance. The contractor shall assume 1 hour of meeting attendance time for this task and the meeting shall be attended by all employees that will be performing the monitoring. Designated monitor may also perform duties of QCM or SSHO.

3.4 INSPECTION

Inspect the work, keep records of work performed, and ensure that gages, targets, ranges, and other markers are in place and usable for the intended purpose. Furnish, at the request of the Contracting Officer, boats, boatmen, laborers, and materials necessary for inspecting, supervising, and surveying the work. When required, provide transportation for the Contracting Officer and inspectors to and from the disposal area and between the dredging plant and adjacent points on shore.

3.5 CONDUCT OF DREDGING WORK

3.5.1 Order of Work

The following table presents a dredge sequencing schedule based upon PNS boat docking dates. Contractor shall confirm docking schedules and adjust the sequencing as required to accommodate PNS scheduling requirements.

Bid Location Estimated CY Max. Overdredge CY Dates Base Bid Berth 6 7,183 8,366 11/08/2020-12/14/2020 Option 1 Berth 14 high spot 181 771 12/14/2020-01/31/2021 Option 2 Berth 12 high spot 283 528 12/14/2020-01/31/2021

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The Base Bid (Berth 6) must be completed with the post dredge hydrographic survey submitted no later than 12/14/2020. These dates are firm due to vessel schedules, and the need for a complete hydrographic survey to be approved and reviewed prior to vessel arrival. If bid options are awarded they may begin only after the Base Bid dredging is completed to the satisfaction of the government.

NOTE 1. Estimated quantities include dredging to design depth and maximum overdredge, as well as the two bid options.

Note 2. Under no circumstances shall any dredging work occur before November 8 or after March 15 of any year as specified in the project permits.

The Contracting Officer’s Representative will direct the Contractor on the order of work. The Government reserves the right to change the order of work at any time.

3.5.2 Interference with Navigation

Contractor shall coordinate all marine vessel movements with the Shipyard’s Port Operations Department. The Contractor shall submit a weekly updated schedule showing proposed dredge locations and vessel movements to the Contracting Officer’s Representative. The Contractor shall meet with Contracting Officer’s Representative and Shipyard Port Operations Representatives weekly to review the schedule.

The Contractor shall minimize interference with the use of channels and passages. The Contracting Officer’s Representative will direct the shifting or moving of dredges or the interruption of dredging operations to accommodate the movement of vessels and floating equipment, if necessary.

Contractor shall maintain a minimum of 100’ of standoff from any berthed submarine and a minimum of 25’ from any berthed barge or support vessel.

3.5.3 Lights

Each night, between sunset and sunrise and during periods of restricted visibility, provide lights for floating plants, pipelines, ranges, and markers. Also, provide lights for buoys that could endanger or obstruct navigation. When night work is in progress, maintain lights from sunset to sunrise for the observation of dredging operations. Lighting shall conform to United States Coast Guard requirements for visibility and color.

3.5.4 Ranges, Gages, and Lines

Furnish, set, and maintain ranges, buoys, and markers needed to define the work and to facilitate inspection. Establish and maintain gages in locations observable from each part of the work so that the depth may be determined. Suspend dredging when the gages or ranges cannot be seen or followed. The Contracting Officer will furnish, upon request by the Contractor, survey lines, points, and elevations necessary for the setting of ranges, gages, and buoys.

3.5.5 Plant

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Maintain the plant, scows, coamings, barges, pipelines, and associated equipment to meet the requirements of the work. Promptly repair leaks or breaks along pipelines. Remove dredged material placed due to leaks and breaks.

3.5.6 Disposal of Excavated Material

Provide for safe transportation and disposal of dredged materials to building 357, and from the Building 357 to the approved landfill.

Transportation shall include measures to prevent loss of material during movement, including water that might separate from the dredge spoils during movement. Contractor is responsible to follow all haul restrictions and requirements imposed by the towns or municipalities in which the haul routes are located. The deposit of dredged materials in unauthorized places is forbidden.

3.5.7 Method of Communication

Provide a system of communication between the dredge crew, the Port Operations of the Portsmouth Naval Shipyard, and the crew at the disposal area. A portable two-way radio is acceptable.

3.5.8 Salvaged Material

Anchors, chains, firearms, and other articles of value, which are brought to the surface during dredging operations, shall remain or become the property of the Government and shall be deposited on shore at a convenient location near the site of the work, as directed.

3.5.9 Safety of Structures

The prosecution of work shall ensure the stability of caissons, piers, berths, bulkheads, fender systems, mooring hardware, and other structures lying on or adjacent to the site of the work, insofar as structures may be jeopardized by dredging operations. Repair damage resulting from dredging operations.

3.5.10 Plant Storage

When not in use, plant equipment shall be stored at an approved location. Stored plant equipment shall not interfere with Portsmouth Naval Shipyard operations.

3.5.11 Plant Removal

Upon completion of the work, promptly remove plant, including ranges, buoys, piles, and other markers or obstructions.

3.6 MEASUREMENT

Contractor shall take soundings before and after dredging.

3.6.1 Method of Measurement

The material removed will be measured by cubic yard in place, by means of soundings taken before and after dredging. The drawings represent existing conditions based on current available information, but shall be verified and

Section 35 20 23 Page 13 corrected, if necessary, by soundings taken before dredging in each locality. Soundings shall be taken by Multi-Beam Sonar methods; as approved by the Contracting Officer, no sooner than 30 days prior to dredging. Post dredge surveys shall be completed immediately following, and in no case greater than 5 business days upon, completion of dredging activity for each designated location. Results of soundings will be the basis for payment.

3.6.2 Surveys During Progress of Work

Contract depth will be determined by soundings as work progresses. The Contractor shall be able to produce drawings with soundings data at any time during dredging operations if requested by the Contracting Officer.

3.6.3 Monthly Estimates

Monthly estimates of work completed will be based on the result of soundings taken during the progress of the work. Deductions will be made for dredging and disposal not in accordance with the specifications.

3.7 FINAL EXAMINATION AND ACCEPTANCE

Contractor shall ensure that existing drains, catch basins, and drainage structures used in the vicinity of the offload site are protected and free of sediment and debris, and freely transport water to the outfalls.

When areas are found to be in a satisfactory condition, the work therein will be accepted as complete. Final volumes will be subject to deductions or correction of deductions previously made because of excessive overdepth, dredging outside of authorized areas, or disposal of material in an unauthorized manner. All material (including hard material in Berth 6A) must be removed down to the design dredge depth for the base bid to receive payment.

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3.7 FINAL EXAMINATION AND ACCEPTANCE