Section 35 20 23 (7 Apr 21) Amendment1.pdf

Redwood City Channel FY21 Maintenance Dredging W912P721B0003

SECTION TABLE OF CONTENTS

DIVISION 35 - WATERWAY AND MARINE CONSTRUCTION

SECTION 35 20 23

DREDGING

04/06

PART 1 GENERAL

1.1 DEFINITION

1.2 SUBMITTALS

1.3 MATERIAL TO BE REMOVED

1.3.1 Scow Monitoring

1.3.1.1 Dredge Data Logging System (DDLS)

1.3.1.2 Dredge Material Disposal Site Log (DMDSL)

1.3.1.3 DDLS Report/Data

1.4 MEASUREMENT AND PAYMENT

1.4.1 Method of Measurement

1.4.1.1 Before-Dredge Survey

1.4.1.2 After-Dredge Survey

1.4.1.3 Required Dredge Prism

1.4.1.4 Allowable (Paid) Overdepth Prism

1.4.1.5 Allowable (Unpaid) Overdepth Prism

1.4.2 Side Slope Prism

1.4.3 Progress Payment Quantity

1.4.4 Final Payment Quantities

1.5 BASIS FOR BIDS

PART 2 PRODUCTS

PART 3 EXECUTION

3.1 INSPECTION

3.1.1 Government QAR Accommodations

3.2 CONDUCT OF DREDGING WORK

3.2.1 Order of Work

3.2.2 Interference with Navigation

3.2.2.1 Coast Guard Notification

3.2.3 Lights

3.2.4 Ranges, Gages, and Lines

3.2.5 Plant

3.2.6 Disposal of Excavated Material

3.2.6.1 Overflow/Decant, Spillage and Leakage

3.2.6.2 Barring and Knock-Down Dredging

3.2.7 Navigation Warnings

3.2.8 Safety of Structures

3.2.9 Plant Removal

3.3 ACCEPTANCE

3.3.1 Reach Acceptance

3.3.2 Reach Rejection

-- End of Section Table of Contents --

SECTION 35 20 23 Page 1 Apr 06, 2021

SECTION 35 20 23 Page 2 Apr 06, 2021

SECTION 35 20 23

DREDGING

04/06

PART 1 GENERAL

1.1 DEFINITION

Dredging work is defined as the removal of bottom sediments including;

clay, silt, sand, and gravel from streams, rivers, lakes, coastal waters, oceans, and transporting the resulting material by barges, ships, or pipelines to a designated placement site on land or in water. Annual O&M maintenance dredging work has a known material that is not hard to dredge. Hard material is defined as material requiring the use of special equipment for economical removal, and includes boulders or fragments too large to be removed in one piece by the dredge.

1.2 SUBMITTALS

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

submittals not having a "G" designation are for information only. Submit the following in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:

SD-02 Shop Drawings

Soundings or Sweepings; G, 35 20 23

Submit drawings of surveys during progress of work by soundings or sweepings

SD-06 Test Reports

Dredge Material Disposal Site Log (DMDSL), 35 20 23-1.3.1.2

1.3 MATERIAL TO BE REMOVED

The recently deposited material to be removed is characterized as silty, sandy, clay (CL, ML per USCS).

1.3.1 Scow Monitoring

The contractor shall comply with the Dredge Data Logging System. The purpose of complying with two different and independent scow monitoring programs is to fulfill obligations from two different and independent government quality assurance agencies.

1.3.1.1 Dredge Data Logging System (DDLS)

Submit the DDLS, the DDLS back-up system, and the qualifications of the DDLS QC firm to the Contracting Officer for approval, as specified in Attachment 1 at the end of the Specification package.

1.3.1.2 Dredge Material Disposal Site Log (DMDSL)

Submit a DMDSL on a weekly basis by noon Monday that enumerates work accomplished during the preceding week. The DMDSL logs to be submitted

SECTION 35 20 23 Page 3 Apr 06, 2021 shall include the reach from where the material cam from. Every Monday, the Contractor shall email the prior week's DMDSL data to the government.

Include the Corps permit number and dredge episode number. Maintain a DMDSL using the "Dredge Material Disposal Site Log" form in Attachment 2 at the end of the Specification package. DMDSL shall be included as an attachment to QC Daily Reports.

1.3.1.3 DDLS Report/Data

Submit electronic copies of the DDLS positional data for all dredge equipment and all disposal/fill vessels utilized; and dredged quantity, sediment type and GPS positional data on the dredge and disposal or fill locations for all scows and barges. This electronic data shall be included in the Dredge daily (CQC) Report submitted in RMS.

1.4 MEASUREMENT AND PAYMENT

1.4.1 Method of Measurement

The Government shall furnish all BD and AD surveys. The material removed will be measured by cubic yard in place (in-situ). The drawings represent existing conditions based on current available information, but will be verified and corrected, if necessary, by soundings taken before dredging in each locality. Results of soundings will be the basis for payment.

1.4.1.1 Before-Dredge Survey

The Before Dredge (BD) Survey is the hydrographic survey that is performed prior to the start of dredging for the purposes of payment in accordance with 01 32 23 (Hydrographic Survey).

1.4.1.2 After-Dredge Survey

The After Dredge (AD) Survey is the hydrographic survey that is performed after the dredging is completed for the purposes of acceptance and payment in accordance with 01 32 23 (Hydrographic Survey).

1.4.1.3 Required Dredge Prism

The Required Dredging Prism is defined by the material above the project depth and in between the channel toes. The total quantity of material required to be dredged will be the material available in the Required Dredging Prism.

1.4.1.4 Allowable (Paid) Overdepth Prism

The depth of the Allowable Overdepth (Paid) Prism is defined by the material below project depth and above the 21.5 -foot Allowable (Paid) Overdepth. The width of the Allowable Overdepth (Paid) Prism is defined by the channel width between the channel toes. Dredging within the Allowable Prism is authorized but not required. Dredging in excess of the allowable 2-foot paid overdepth is prohibited.

1.4.1.5 Allowable (Unpaid) Overdepth Prism

The depth of the Allowable (Unpaid) Overdepth Prism is defined by the

SECTION 35 20 23 Page 4 Apr 06, 2021 material below the 1.5-foot Allowable (Paid) Overdepth and above the 2-foot Allowable Overdepth (Paid plus Unpaid). The width of the Allowable Overdepth (Unpaid) Prism is defined by the channel width between the channel toes. Dredging in this Prism is authorized but not required.

Dredging in excess of the allowable 2-foot overdepth is prohibited.

1.4.2 Side Slope Prism

The Side Slope Prism is the area outside of the channel toes. Dredging on the side slope is prohibited. Material that sloughs from the side slope into the channel and is removed will be paid as evidenced by the Before-and After-Dredge surveys.

1.4.3 Progress Payment Quantity

The material quantity for progress payments will be ninety percent (90%) of the payable quantity calculated using the Government's payment survey and the Before-Dredge survey, less any previously paid quantities. No payment shall be made for Side Slope material.

1.4.4 Final Payment Quantities

The final payment quantities for each reach will be 100% of the payable quantity calculated from the Before-Dredge and After-Dredge surveys, less any prevailing paid quantities using the TIN to TIN method in EM 1110-2-1003. The Government survey shall be used unless there is evidence of collusion, fraud, or obvious error documented.

1.5 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. Include a bid unit price per cubic yard of dredging based on the quantity as specified or indicated. If the Contracting Officer or delegated representative requires an increase or a decrease in total volume of dredging, the contract price will be adjusted. 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.

PART 2 PRODUCTS

Not used.

PART 3 EXECUTION

3.1 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.

SECTION 35 20 23 Page 5 Apr 06, 2021

3.1.1 Government QAR Accommodations

The Contractor shall provide, upon request of the Government QA Representative (GQAR), suitable transportation from all points on shore designated by the GQAR to and from the various pieces of plant, and to and from the dredging and disposal areas. Transportation will be made available any time during dredging operation or when the Contractor is working, when requested by the GQAR. Contractor should anticipate at least two round trips per 24-hour period. Contractor shall provide GQAR access to a desk, or other suitable workspace including electrical outlet, while on-board the dredge plant. Should the Contractor refuse, neglect, or delay compliance with these requirements, the specific transportation facilities may be furnished and maintained by the Contracting Officer or delegated Representative, and the cost thereof will be deducted from any amounts due, or to become due the Contractor.

3.2 CONDUCT OF DREDGING WORK

3.2.1 Order of Work

The Contracting Officer or delegated representative will direct the Contractor on the order of work. The Government reserves the right to change the order of work at any time.

3.2.2 Interference with Navigation

Minimize interference of channels and passages. The Contracting Officer or delegated 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.

3.2.2.1 Coast Guard Notification

The Contractor shall submit copies of written Coast Guard notifications prior to conducting dredging activities. Utilize the Dredging Plan to forecast the activities in the channels and shall notify the United States Coast Guard Marine Safety Office in writing with a copy to the Contracting Office Representative. Coast Guard notification shall be provided in accordance with Section GOVERNMENT SAFETY REQUIREMENTS-DREDGING 01 35 26-

3.10.3 U.S. Coast Guard Notification and 3.12 Marine Transportation Safety. When utilizing the Government-furnished open water disposal area, notify the U.S. Coast Guard in accordance with Section AQUATIC DISPOSAL 35 20 24-3.6.6 Notification. All dredge plants must be equipped with an Automatic Identification System (AIS) transponder that is compatible with Coast Guard specifications identified in Section GOVERNMENT SAFETY REQUIREMENTS-DREDGING 01 35 26-3.12.2 Vessel Traffic Services (VTS) Reporting Requirements.

3.2.3 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.

SECTION 35 20 23 Page 6 Apr 06, 2021

3.2.4 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 or delegated representative will furnish, upon request by the Contractor, survey lines, points, and elevations necessary for the setting of ranges, gages, and buoys.

3.2.5 Plant

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.

3.2.6 Disposal of Excavated Material

Provide for safe transportation and disposal of dredged materials at the Government-furnished in-bay disposal site SF-11 and a Contractor-furnished beneficial use upland site, unless otherwise directed by the Contracting Officer or delegated representative. The deposit of dredged materials in unauthorized places is forbidden. Comply with rules and regulations of local port and harbor governing authorities.

3.2.6.1 Overflow/Decant, Spillage and Leakage

Spillage and leakage are prohibited during transportation to the disposal site.

3.2.6.2 Barring and Knock-Down Dredging

Barring, dragging and all other methods of bed leveling are prohibited.

3.2.7 Navigation Warnings

Furnish and maintain navigation warning signs along the pipeline.

3.2.8 Safety of Structures

The execution of work shall ensure the stability of piers, bulkheads, 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, insofar as such damage may be caused by variation in locations or depth of dredging, or both, from that indicated or permitted under the contract.

3.2.9 Plant Removal

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

3.3 ACCEPTANCE

3.3.1 Reach Acceptance

Acceptance of Reach(es) will be in writing from the Contracting Officer Representative based on the Government After-dredge multi-beam survey plan

SECTION 35 20 23 Page 7 Apr 06, 2021 view plots using 5' X 5' bin data. The government will accept the reach within 7 calendar days of being notified of reach completion.

3.3.2 Reach Rejection

If the Contracting Officer Representative finds the after-dredge survey of the reach to be unacceptable, the Contractor shall resume dredging or barring, in accordance with Section 35 20 23 DREDGING, until the work is complete. The Contractor is responsible for time required for dredging or barring to remove shoals, lumps or other lack of contract depth and for the time required to resurvey the rejected Reach. When the dredging or barring is complete, the after-dredge survey process, starting with the Contractor's written Request for Acceptance Survey, is then repeated except that the Contractor is liable for subsequent Government survey costs. The Contractor will be assessed $10,000 per day that the Government spends on after-dredge surveys of a Reach that is rejected after the first Government after-dredge survey. The Government's efforts include time spent on station waiting, surveying time and after-survey data processing and reporting. A partial day of survey efforts by the Government will be billed as a full day.

-- End of Section --

SECTION 35 20 23 Page 8 Apr 06, 2021