W912DW20B0005- Kenmore Dredging Specification-Partial.pdf

FY20 Kenmore Navigation Channel Maintenance Dredging 20014 Kenmore, WA

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SECTION 35 20 23

DREDGING

PART 1 GENERAL

1.1 GENERAL INFORMATION

All materials shall be dredged by clamshell dredge, placed in/on a sealed flat top (non-bottom dumping) barge and the free liquid dewatered, dewatered dredged material shall be transported to a Contractor-specified, Government approved, Transload facility/location, and transloaded to sealed containers/trucks for transport to an approved Contractor-specified upland Disposal facility. All shoals shall be removed despite any changes that may have occurred in their volume, dimensions, or locations between bathymetric surveys.

The Contractor shall be responsible for the dredging, dredged material management including dewatering, transport, transloading, and the disposal.

The sediment to be dredged is unsuitable for open water disposal and shall be managed accordingly – see SECTION 35 20 24 UNSUITABLE MATERIAL TRANSPORTATION, TRANSLOADING, AND DISPOSAL.

It is the Bidder’s responsibility to be thoroughly familiar with the weather and lake conditions for the project location and an understanding of the water lake levels in the work area. Pre-bid site visits are recommended. See FAR 52.236-4 PHYSICAL DATA for additional information.

All work shall be of good quality, free from fault or defect, and in accordance with the requirements of these contract specifications and plans. Any work not conforming to the contract specifications and plans, including unapproved or unauthorized actions shall be considered defective. The Contractor shall promptly correct all defective work or work that otherwise fails to conform to the requirements of the contract documents, at no expense to the Government.

In the event the required dredging depth cannot be reached, the Contractor shall be required to dig to refusal and document that the dredging depth cannot be reached.

1.2 SUBMITTALS

Government approval is required for submittals with a “G” designation; submittals having an “F” are for information only. The following shall be submitted in accordance with SECTION 01 33 00.

SD-01 Preconstruction Submittals

Work/Construction Plan; G

1.3 DREDGING AND DISPOSAL WORK PLAN

Contractor shall submit a Dredging and Disposal Work Plan (Work Plan) within fourteen (14) calendar days of Notice to Proceed (NTP). The Work Plan shall thoroughly describe the Contractor's plan to execute and complete this project.

The Contractor’s Work Plan shall include a description of mobilization/demobilization, shall document and describe the proposed equipment, means, and methods of accomplishing the dredging, handling, transportation, transloading and disposal of sediment and debris. The Work Plan shall describe the proposed survey controls (horizontal and vertical i.e. depth) that will be utilized to demonstrate that dredging is being completed in accordance with the design dredging prism.

The Work Plan includes, but is not limited to, the following elements:

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a) General project description and information, list of employees (prime and primary subcontractor(s)) including role and responsibilities, equipment (prime and subcontractor(s).

A description of the organization, including a chart showing lines of authority and acknowledgment. Include a Project Superintendent, CQC System Manager, site health and safety representative, equipment operator(s), and other key personnel deemed necessary by the Contractor for the successful implementation and completion of this work.

b) Description of the means and methods to complete the required work. Prepare a work area plan showing the proposed activity in each portion of the work area(s) and identify the areas of limited use or nonuse. Include measures for marking the limits of use areas, including methods for protection of features to be preserved within authorized work areas and methods to control runoff and to contain materials on site, a site plan, and a traffic/pedestrian control plan. Other elements to include are task sequencing including description and figures of work areas, equipment details and use, site management (civilians, traffic, visitors, etc.), approved techniques, loading methods, transportation methods, surveying and mapping plan, proposed temporary excavations or embankments for haul roads, stream crossings, jurisdictional wetlands, material storage areas, structures, sanitary facilities, storm drains and conveyances, and stockpiles, Disposal facility, equipment and cleanup plans, maps of facilities and emergency contact information. Content can be narrative, charts, tables, drawings, and/or figures.

c) Contact information (Contractor(s)/subcontractor(s) and government), emergency information, lines of communication between Contractor(s), subcontractor(s), and government. Provide 24-hour direct telephone numbers for key staff that will be responsible during off hours work periods and on non-working days.

The Contractor shall submit a detailed written TRANSLOAD, TRANSPORT, AND DISPOSAL Work Plan (TTD) to address activities associated with handling, transport, transloading and disposal of the dredge material. The TTD shall be a separate document from the Dredging and Disposal Work Plan (DDWP). See 35 20 24 for TTD Plan details.

1.4 GOVERNMENT RECORDS

Government records of previous dredging, previous pre-dredge bathymetric surveys, post-dredge bathymetric surveys, detailed current condition bathymetric surveys, coordinates and descriptions of survey monuments, sediment gradation curves, and exploration logs (if any of the previous exist) are available for inspection in Operations Division, Seattle District, U.S. Army Corps of Engineers, 4735 East Marginal Way South, Seattle, Washington. Point of Contact is John Pell, phone (206) 764-3413. Government does not warrant accuracy of records of previous dredging.

1.5 CHARACTERISTICS OF MATERIAL

Sediments in the navigation channel are primarily clays, silts, sands loamy sediment (CL-ML) with relatively low total solids content. The Contractor may encounter accumulations of forest trash, sunken logs, stumps, human-made wood products, wire, and synthetic rope, metal debris, fishing nets, tires and other miscellaneous debris that periodically may cause production delays.

Bidders are expected to examine the site of work and verify the character of materials.

Classification and description of the materials to be dredged is classified according to Attachment 35 20 23-A: U.S. Geologic Survey (USGS) Wentworth Grade Scale.

1.6 ARTIFICIAL OBSTRUCTIONS

Except as indicated, the Government has no knowledge of cables, pipes, or other artificial obstructions or of any wrecks, wreckage, or other material that would necessitate the use of explosives or the employment of additional equipment for economical removal. If actual

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conditions differ from those stated or shown, or both, an adjustment in contract price or time for completion, or both, will be made in accordance with "FAR 52.236-2, Differing Site Conditions."

1.7 MINIMUM AND MAXIMUM PAY DEPTH

The Contractor shall dredge available material from the work area necessary to complete the work specified, whether or not the actual quantities available are less than the estimated quantity awarded. Additional volume, above the estimated quantity awarded may be awarded at the discretion of the Contracting Officer. The Contractor shall not exceed the estimated quantities in the awarded Contract bid line items without prior specific authorization, and only with a signed contract modification issued by the Contracting Officer. The work shall be done in accordance with this Contract and at the Contract Line Item price.

To cover inaccuracies of the dredging operation within the area to be dredged, a Minimum (Required) Pay Depth, Maximum Pay Depth, and Maximum Dredging Depth has been established. The volume to be dredged above the Minimum Pay Depth (including associated side slopes) is referred to as the required dredging prism. The volume between the Minimum and Maximum Pay Depth (including associated side slopes) constitutes the allowable paid overdepth.

Paid Allowable Overdepth (Maximum Pay Depth) is up to two (2) feet below the required minimum dredging depth and within the dredging limits.

1.8 MINIMUM / REQUIRED AND MAXIMUM DREDGING DEPTHS

a) Lake Washington Low Water Datum (LWLW) – Convert from NAVD88 to LWLW by adding16.75 FT. Convert from MLLW (NOAA Tide Station 9447130 Seattle, WA) to LWLW by adding 19.09 FT.

1. NAVD88 + 1.75 ft = -15 ft LWLW

2. MLLW + 4.09 ft = -15 ft LWLW

b) MINIMUM / REQUIRED DREDGING DEPTH is -15 ft LWLW.

c) The Contractor shall dredge to the REQUIRED/MINIMUM DREDGING DEPTH. The Contractor may be required to go back and remove any material remaining above the

REQUIRED/MINIMUM DREDGING DEPTH.

d) Allowable paid Overdepth is 2 feet. No Advance Maintenance is authorized.

e) MAXIMUM DREDGING DEPTH (equals Maximum Paid Depth) is -17 ft LWLW.

1.9 SIDE SLOPES AND END TRANSITIONS

Dredging shall only be from toe of slope across the authorized channels and turning basin to toe of slope (box cut between toes). Estimated quantity accounts for material at the channel transitions, in both the side slopes and box. However, the material on the side slope and end transitions may not displace into the box while excavating, and full estimated volumes may not be achieved. If side slope or end transition material displaces at any time (prior to acceptance) during the work window, it is the responsibility of the Contractor to clear the channel to Minimum required Pay Depth. The amount of material displaced from side slopes will be determined by bathymetric survey.

Dredge uniform sloped end-cut transitions from existing channel depth to required dredging depth.

1.10 EXCESSIVE DREDGING AND CORRECTIVE ACTION

Soundings or sweepings will be taken behind the dredge to determine if material has been removed outside the contract limits.

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Material taken from beyond limits as defined in paragraphs Minimum and Maximum Pay Depth and Maximum Dredging Depth and Side Slopes and End Transitions, above, will be deducted from the total amount dredged as excessive dredging for which payment will not be made.

Nothing herein shall be construed to prevent payment for removal of shoals performed in accordance with applicable provisions of either paragraphs FINAL EXAMINATION AND ACCEPTANCE or SHOALING of Section 01 00 02, SUPPLEMENTARY REQUIREMENTS

FOR DREDGING.

The Contractor shall use extreme care when conducting dredging operation to not to exceed the MAXIMUM DREDGING DEPTH or dredge outside the specified dredge prism. The Contractor shall bear sole responsibility for any dredging beyond MAXIMUM DREDGING DEPTH, which may occur because of its operation.

Material dredged from beyond the MAXIMUM DREDGING DEPTH will result in the COR immediately reporting a water quality non-conformance incident to WA Ecology. WA Ecology may require immediate corrective action, which will be accomplished by the Contractor at the Contractor’s expense. Dredging will be immediately discontinued until the cause of the excessive dredging is identified and corrected, and all corrective action is completed satisfactorily.

The Contractor will specifically notify the Contracting Officer Representative (COR), in writing, once the Contractor reaches approximately 75 percent of the quantities specified in the Contract Line Items. This notification will be separate and in addition to other reporting required elsewhere in this Contract. It is the Contractor’s responsibility to notify the Government as soon as the estimated quantities are identified to be insufficient to complete the work indicated and specified.

This provision shall not be interpreted as an order for the Contractor to stop work upon reaching 75 percent of the estimated quantities; it merely requires notice and potential corrective action at that point. However, absent further specific direction, the Contractor shall be prepared to stop work on any CLIN at no additional cost to the Government once 100 percent of the line item quantity has been obtained.

1.11 DREDGING RESTRICTIONS

All construction work shall be restricted to the dredging work window between (0001 hours) 16 November 2020 through midnight (2359 hours) 01 February 2021. No in-water work is authorized outside the established work window.

Conduct water quality monitoring in accordance with the Water Quality Monitoring Plan (WQMP), dated 1 June 2020 (Attachment 01 57 20.00 10-A).

Where pre-dredge bathymetric surveys show conditions at or below the required dredging prism, no dredging shall be performed unless approved by the COR.

Dredging beyond the MAXIMUM DREDGING DEPTH is not allowed.

The time stated for completion shall include final cleanup of the premises.

1.12 DREDGING SEQUENCE OF WORK

The Contractor shall describe the proposed sequence of work in the Work Plan. The Government reserves the right to change the order of work at any time. Dredging sequencing will be discussed during the Pre-Construction meeting prior to the start of mobilization. Variations in the dredging and disposal sequence may be considered. The Contractor must submit a revised Work Plan and receive COR approval before deviating from a previously approved sequence of work.

1.13 STAGING AREAS

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Contractor is responsible with obtaining any staging areas. After the Contractor completes his operations, the staging area shall be restored to a condition equal to that existing before Contractor’s operations. Government will not be responsible for Contractor’s equipment and materials in the staging area and Contractor shall provide his own security.

1.14 LIGHTS, LIGHTED BUOYS AND DREDGING AIDS MARKERS

All existing lights, lighted buoys and dredging aids markers must be maintained, operable and on station at all times to insure a safe harbor. Damaged navigation aids, lights and markers caused by Contractor’s actions shall be reported to the U.S. Coast Guard and the COR immediately.

Contractor is responsible for all costs to repair damaged navigation aids, lights, and markers.

While dredging and when in the dredging work area, Contractor must use appropriate lights, markers and buoys to allow safe passage in and around the navigation channel and adjacent areas.

1.15 REPORTING REQUIREMENTS

Reference Section 01 45 00.15 10 RESIDENT MANAGEMENT SYSTEM CONTRACTOR MODE (RMS CM). Contractor shall prepare and maintain a daily report of operations and furnish one copy thereof to COR daily. Further instructions on preparation of report will be furnished at the preconstruction conference. Contractor shall record times, durations, and reasons of all shutdowns during the dredging period.

1.16 PLANT AND EQUIPMENT AVAILABILITY

Keep all necessary dredge equipment and attendant plant, and equipment on the job to meet the requirements of the work. The dredge equipment and attendant plant and other equipment shall be in satisfactory operating condition and capable of safely and efficiently performing the work as set forth in specifications and shall be subject to inspection by the COR at all times.

1.17 COVID-19 CONTINGENCY

Contractor shall comply with all local, state, or federal COVID-19 restrictions and/or requirements.

Contractor is responsible for the health and safety of Contractor personnel.

Contractor shall ensure dredge plant and other equipment, labor, materials, appliances, services, or incidentals, to perform all operations necessary to construct and complete the items in accordance with these specifications and the applicable drawings, is available during the contract period of performance.

No separate payment will be made for the Contractor to obtain and maintain project equipment, labor, materials, or services, and to perform all operations necessary to construct and complete the project in accordance with these specifications and the applicable drawings, according to local, state, and federal COVID-19 restrictions and/or requirements.

PART 2 PRODUCTS

NOT USED.

PART 3 EXECUTION

3.1 INSPECTION

Contractor shall inspect the work, keep records of work performed, and ensure that gages, and other markers are in place and usable for the intended purpose. Contractor shall record times, durations and reasons of all shutdowns during the dredging day. See Section 01 45 00.00 10 QUALITY CONTROL and Section 01 45 00.15 10 RESIDENT MANAGEMENT SYSTEM CONTRACTOR MODE (RMS CM) for reporting requirements.

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Contractor shall furnish, at the request of the COR, boats, boatmen, laborers, and materials necessary for inspecting the dredging activities. When required, provide transportation for the COR and other Government inspectors to and from the Disposal facility and between the dredging plant and adjacent points on shore.

3.2 SHALLOW DEPTH CHANNEL

a) There are areas outside of the project dredging area that are shallower than the authorized navigation channel depths. It is the responsibility of the contractor to evaluate the depths and clearances on the drawings and to account for the controlling depths when submitting a proposal.

3.3 CONDUCT OF DREDGING WORK:

a) Interference with Navigation:

1) The contractor shall minimize interference with the use of channels and passages. If the Contractor’s plant does obstruct the Channel and makes passage of vessels difficult or endangers them, the plant shall be promptly moved on the approach of a vessel as far as may be necessary to afford a practicable passage.

b) Interference with Aircraft:

1) Dredging area is located adjacent to an area frequented by waterborne aircraft (Kenmore Air).

The contractor shall minimize interference with aircraft as much as possible. If the Contractor’s plant does obstruct the long term airspace and makes passage of airplanes difficult or endangers them, the plant shall be promptly moved on the approach of a scheduled aircraft as far as may be necessary to afford a practicable transit. It is the Contractor’s responsibility to arrange with Kenmore Air or designee to allow both dredging and flight operations to continue.

c) Lights:

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

d) Layout of Work:

1) Prior to beginning dredging, the COR will establish a tidal reference point on one navigation aid or other suitable structure. Contractor shall use the reference points for his elevation control. Centerline range alignment may vary from the channel alignment. Contractor’s use of ranges for positioning shall be at his own risk; see Section 00 72 00 CONTRACT CLAUSES, Paragraph LAYOUT OF WORK.

e) Salvaged Material

1) 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 Contractor. All material shall be removed from the work area as part of the construction process. No additional payment will be made for disposal of these items.

f) Safety of Structures

1) The prosecution 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. The contractor shall maintain a minimum standoff distance of twenty five (25) feet from all piling structures and timber walls unless otherwise authorized by the

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COR. The Contractor shall repair at their own expense, 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.

g) Plant Removal

1) Upon completion of the work, the Contractor shall promptly remove its plant, including ranges, buoys, piles and other markers or obstructions placed under this Contract.

h) Debris

1) The Contractor may encounter natural debris such as forest debris, sunken logs, stumps, made wood products, wire and synthetic rope, metal debris, fishing nets, tires and other miscellaneous natural and artificial debris. Any debris larger than 2 feet in any dimension shall be removed from the dredged material, and disposed in an appropriate upland disposal facility. No natural or artificial debris is allowed in the open water disposal sites. No additional payment will be made for disposal of debris and shall be considered incidental to the dredging operation.

3.4 DREDGING

Clamshell dredging shall be conducted in a manner that shall result in minimum turbidity and suspended sediment using Dredging Best Management Practices (BMPs) – see Attachment 35 20 23-B.

Dredging shall be performed using a mechanical rehandling or environmental (or similar) bucket, without teeth, to reduce turbidity and dredging beyond the maximum dredging depth (overdredging/excessive dredging). The dredged material and entrained water must be managed in an environmentally appropriate manner.

Dredging outside the contract dredge area is not allowed. In addition, dredges shall be furnished at all times with an operating and easily readable dredging depth indicator.

Dredging shall be performed in such manner that shall not exceed water quality requirements as stated in the applicable Water Quality Monitoring Plan (01 57 20.00 10-A).

During clamshell dredging, the ascent and descent of the clamshell bucket shall be controlled to minimize spillage and elevated turbidity in the water column.

Partial clamshell loads of material shall not be dumped back into the water. Scow overflow is not allowed. Chapter 173-201A WAC “Water Quality Standards for surface waters of the State of Washington” shall be met.

The Contractor shall outfit his dredge disposal barge(s) to provide containment of dredged material as described in the Transload, Transport, and Disposal Work Plan (TTD) prepared by the Contractor, and approved by the Government.

Contractor shall meet Chapter 173-201A WAC “Water Quality Standards for surface waters of the State of Washington.”

3.5. DEWATERING, TRANSPORT, TRANSLOADING

The required work consists of removing material unsuitable for open water disposal from the channel, placing it on a sealed barge, reducing the amount of liquid in the dredged material as much as practicable, decanting surface water in place in an environmentally appropriate manner while filtering/reducing particulates from re-entering the water, transporting the dredged material (soil, sediment, rock, debris and water (free and entrained in the dredge material) from the Kenmore channel to the Contractor-specified (approved by the Government) Transload facility, offloading the material from the barge to the Transload facility, processing the material for

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transport, and disposing the material in a Contractor-specified (approved by the Government) upland Disposal facility permitted to accept the material. Requirements for dewatering, transport, and transloading are provided in Section 35 20 24 – UNSUITABLE MATERIAL

TRANSPORTATION, TRANSLOADING, AND DISPOSAL

3.6 DISPOSAL OF DREDGED MATERIAL

The Disposal facility(s), identified by the Contractor, shall be approved by the Government prior to the start of dredging. See 35 20 24 UNSUITABLE MATERIAL TRANSPORTATION, TRANSLOADING, AND DISPOSAL, paragraph DISPOSAL FACILITY.

No dredged material shall be returned to or placed in open water.

Barge position shall be verified by the National Dredging Quality Management (DQM) Program equipment and monitoring system. The Contractor shall log each transport/transload operation.

The deposit of dredged materials in unauthorized places is forbidden. Comply with rules and regulations of local port and harbor governing authorities.

All debris collected during the dredging operations destined for disposal shall be disposed of at a facility authorized to receive the material, at no additional expense to the Government.

3.6 METHOD OF DISPOSAL

Once the sediment is removed from the channel, it shall be contained, at all times, within a sealed container (scow, truck, etc.) during dewatering, transit from the work site to the transload facility/location, transloading, and transit to the Disposal facility.

3.8 DEFECTIVE WORK

Work that does not conform to the contract specifications and plans will be considered defective.

Upon notice from the COR of defective or non-conforming work, the Contractor shall, within seven (7) days, correct the defective work or provide a written plan to the COR describing the corrective action and schedule to perform the corrective action.

If the Contractor refuses or neglects to correct the defects, then the Government may obtain, use and employ materials, labor, tools and equipment to perform the corrective action and the expense of the Government’s actions shall be deducted from moneys which may otherwise be then due or may become due to the Contractor.

The Government may, at its sole option, elect to accept defective or non-conforming work. In such case, the Government shall reduce the Contract Price to account for such defective or non-conformance work.

3.7 NATIONAL DREDGING QUALITY MANAGEMENT PROGRAM SPECIFICATION

The National Dredging Quality Management (DQM) Program specification is included as Attachment 35 20 23-C. The DQM is an automated dredge contract monitoring system used to view real time dredge information in GIS. The requirements of this specification shall be implemented to the extent noted in the edited version of the attached DQM specification.

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