Sec_35_20_23_Dredging.pdf

DIVISION 35 WATERWAYS AND MARINE

35 20 23-1

SECTION 35 20 23

DREDGING

1 GENERAL

1.1 SUMMARY

Perform all operations necessary for the removal of all materials to the required dimensions as shown on the drawings, the satisfactory disposal thereof, and all operations thereto. The work includes providing and maintaining the hydraulic pipeline from dredging site to the disposal site, the construction and maintenance of disposal earth berm, and leveling the grade of all new disposed material within the disposal area. If nighttime operations are to be conducted the contractor shall inform the contracting officer and comply with lighting requirements listed in paragraph 3.2.2 of this section.

1.2 REFERENCES

The publication listed below form a part of this specification to the extent referenced. The publications are referred to in the text by the basic designation only.

CODE OF FEDERAL REGULATIONS (CFR)

29 CFR 1910 Occupational Safety and Health Standards

1.3 SUBMITTALS

Submit the following in accordance with Section 01300, "Submittals."

1.3.1 Dredging Plan

Submit a detailed plan of the entire dredging and dredge material disposal operation including a list of equipment, environmental controls, means of transport, and means and locations of intermediate storage or handling of dredge material. This submittal is required 21 days prior to start of work. Provide plans and procedures should gale force winds or higher be forecast. Precautions shall include, but not be limited to, closing all openings, removing all loose materials, tools and equipment from exposed locations, anchoring and tying down barge, and removing or securing scaffolding and other temporary work

1.3.2 Hydrographic Survey Drawings

Submit results of hydrographic surveys taken before and after dredging. The pre-dredge survey submittal is required prior to dredging operations and the post-survey submittal is required prior to final acceptance of the completed work.

1.3.3 Dredge Volume Calculations

Submit results of actual gross and design volume of dredged material. Cover sheet shall be signed, dated and sealed by the licensed surveyor.

1.4 CHARACTER OF MATERIALS

All shoal material within the basin limits has occurred since the last maintenance dredging job in fall 2012.

The shoal material is expected to be predominantly silty-clay and possibly construction debris (concrete rubble, etc). Insitu rock , if encountered, shall not be dredged. Debris (trash, junk) may exist in the channel.

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1.5 ARTIFICIAL OBSTRUCTIONS

The Government anticipates debris such as, but not limited to, metal bands, pallets, pieces of broken cable, rope, hose, and broken piles. The Government has no knowledge of existing wrecks, wreckage, or other material of such size or character as to require the use of explosives or special or additional plant for its economical removal. Prior to dredging, the Contractor shall rake the dredge area and remove debris encountered. Debris removed from the dredged area shall be removed from the water. Explosives shall not be used under any circumstance. Disposal of debris shall be the responsibility of the Contractor and disposal shall be outside the limits of USCG Station New Orleans property.

1.6 QUANTITY OF MATERIAL

1.6.1 Overdepth Dredging

To cover unavoidable inaccuracies of dredging processes, removal of material to a depth of one foot below the elevation –10.0 feet MLLW depth specified and within the dredging limits will be allowed.

1.6.2 Side Slopes

Side slopes at the side limits of the dredge area shall be 4:1 (horizontal:vertical). Project the side slope from the dredged bottom elevation at the limits of the dredge area line outward until it intersects the existing bottom of the adjacent waterway. Dredging on side slopes shall follow, as closely as practicable, the lines indicated on referenced drawings. One of the sides of the dredged area along the pier as indicated in the site plan shall be a nearly vertical box cut.

1.6.3 Slides

In the event sliding occurs in any excavation after its completion but prior to its acceptance, the Contractor shall remove such portions of the slide at no additional cost to the Government. In particular, the contractor shall follow up on the vertical box cut in the vicinity of the South concrete bulkhead.

1.7 OBSTRUCTION OF WORK AREA

The Government will undertake to keep the boat basin free from vessels or other obstructions. The Contractor will be required to conduct the work in such manner as to obstruct navigation as little as possible, and in case the Contractor’s plant so obstructs the navigable waters as to make difficult, or endanger the passage of any vessels, said plant shall be promptly moved on the approach of any vessel to such an extent as may be necessary to afford a practicable passage. Upon completion of the work the Contractor shall promptly remove his plant, including pipeline, ranges, buoys, piles, pipeline, and other marks placed by him under the contract in navigable waters or on shore. The Coast Guard will need access to the facilities during the work period and in some instances it may be an emergency. The Contractor’s plant must have the ability to be maneuvered from the boat basin immediately following direction by the Coast Guard. One emergency movement of the Contractor’s plant should be included in the bid price.

2 PRODUCTS

Not used.

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

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Officer and/or COR, boats, boatmen, laborers, and materials necessary for inspecting, supervising, and surveying the work.

3.2 CONDUCT OF DREDGING WORK

3.2.1 Interference with Navigation

Minimize interference with the use of channels and passages. The Contracting Officer 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 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.

3.2.3 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.

3.2.4 Plant

Maintain the plant, scows, coamings, barges, pipelines, and associated equipment to meet the requirements of the work. Monitor and promptly repair leaks or breaks along the pipeline.

3.2.5 Disposal of Excavated Material

Provide for safe transportation and disposal of dredged materials. Transport and dispose of dredged material in the area designated for disposal of dredged material. The deposit of dredged materials in unauthorized places is forbidden.

3.2.5.1 Method of Disposal

The material excavated from the boat basin shall be transported by hydraulic pipeline to the upland disposal location indicated. The use of floating and submerged discharge lines is authorized; the Contractor shall ensure compliance with the provisions in this Specification Section The contractor must also ensure minimal disturbance of the shoreline areas.

3.2.5.2 Disposal in Indicated Fill Area

Discharge into the disposal area shall be coordinated with the USACOE Savannah District, OP-NN Attn.

Mr. Burton Moore. No alternate disposal will be allowed. The Contractor will pump the material via pipeline to the indicated disposal site. No deviation from the shore pipeline route (Road J) will be permitted. Provide and maintain necessary bulkheads, dikes, ditches, spillways, and other construction necessary to confine and retain the fill in the dredge fill area.

3.2.6 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.

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3.2.7 Working in the Vicinity of Structures

The Contractor shall exercise caution when working in the vicinity of structures adjacent to and within the piers and bulkheads. Repair of any damage resulting from excessive or improper excavation of the basin shall be the responsibility of the Contractor. When dredging to obtain the required dimensions might endanger any structure, the Contracting Officer, upon request, may reduce the required excavation in the vicinity of such a structure.

3.2.8 Plant Removal

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

3.2.9 Work Safety

Comply with 29 CFR 1910.

3.3 DISPOSAL SITE

Transport the dredge sediment by submerged hydraulic pipeline to the Ga DOT Sediment Placement Facility on Andrews Island. Comply with all requirements the U.S. Army Corps of Engineers for use of the facility.

3.3.1 Prevention and Damage

The dredged material shall be transported and deposited in such a manner as to insure that no damage will concur to highways, levees, drainage systems, pipelines, utilities, structures, revetments, or other improvements.

3.3.2 Disposal Operation

During disposal operations the Contractor will provide constant radio contact between the personnel on the dredge, at the disposal area, and at the pipeline. The Contractor's disposal area and pipeline personnel are to quickly notify the dredge operator should the disposal area discharge exceed water quality standards, of dike failure, and of pipeline leakage. The Contractor shall inform the Contracting Officer’s Technical Representative (COTR) daily of all problems associated with the dikes, pipeline or disposal area discharge. The time or occurrence and of corrective action to problem should also be reported. Plant downtime to meet water quality standards or to make dike or pipeline repairs will be at no cost to the Government or a basis for a time extension.

3.3.3 Placement of Material

During placement in the disposal area, the Contractor shall perform inspections of the pipeline, dike, and weir discharge at least twice daily. Dredging shall be immediately suspended when necessary and for the time period required to achieve and maintain water quality standards of the discharge from the disposal area. Also, dredging shall be immediately suspended in the event of imminent or actual dike failure or pipeline leakage. Dredging will not resume until dike and/or pipeline repairs have been completed.

3.3.4 Misplaced Material

Material deposited outside of the disposal area or above the maximum indicated elevation will require removal or degrading of such material at the Contractor's expense.

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3.3.5 Deposit in Non-Approved Areas

Any material that is deposited elsewhere than in the disposal area shown on the Site Plan will be required to be removed and deposited in the approved area at no additional expense to the Government.

3.3.6 Floating and Submerged Pipelines

Provide and maintain navigation warning signs along the pipeline. If a leak occurs in the discharge pipeline, immediately discontinue using the line until leaks are repaired. Remove material placed due to leaks or breaks.

3.3.6.1 Submerged

In the event that the Contractor elects to submerge a pipeline constructed of semi-buoyant material, such as PVC pipe or similar low density material, the Contractor shall securely anchor the pipeline to prevent the pipeline from lifting off the bottom under any conditions. The Contractor shall make daily underwater inspections of the submerged pipeline to ensure buoyancy has not loosened the anchors. The Contractor shall remove all anchors when the submerged pipeline is removed. The location of the entire length of pipeline shall be marked with signs, buoys, lights, an flags conforming to the Federal navigational regulations.

3.3.6.2 Floating

Should the Contractor's pipeline not rest on the bottom, it will be considered a floating pipeline and shall be visible on the surface and be clearly marked. In no case will the Contractor's pipeline be allowed to fluctuate between the surface and the bottom, or lie partially submerged. Lights shall be installed on the floating pipeline. The lights shall be supported either by buoys or by temporary piling, provided by the Contractor and approved by the Contracting Officer.

3.3.7 Excessive Discharge Pipe Leakage

Excessive leakage of the discharge pipe shall be sufficient cause for the Contracting Officer to require the Contractor to cease pumping until corrective measures are taken.

3.3.8 Disposal Site Maintenance

The contractor shall relocate the slurry control pipe as required to ensure an even distribution of material throughout the disposal area.

3.4 MEASUREMENT

Contractor shall provide hydrographic surveys before and after dredging. The hydrographic surveys shall be performed by an independent surveyor licensed to perform such work by the State of Georgia. The vertical datum for all soundings shall be Mean Lower low water (MLLW). These surveys shall be used to calculate the actual gross volume and design volume of dredged material removed.

3.4.1 Method of Measurement

The material removed will be measured by cubic yard in place, by means of soundings taken before and after dredging. The contract drawings represent existing conditions based on current available information, but will be verified and corrected by the Contractor, if necessary, by soundings taken before dredging. Prior to start of dredging operations five copies of the pre-dredge survey shall be submitted to the Contracting Officer. Upon completion of the dredge, the Contractor shall perform a post-dredge survey. This, along with the pre-dredge survey, shall be the sole source used to calculate the actual gross volume of dredged material. The design volume is the volume within the design template that

35 20 23-6 consists of the bottom of basin at the dredge depth including the allowable overdepth and the specified side slopes. The surveyor who performed the surveys shall calculate the gross volume and design volume from the results of the surveys. The Contractor shall submit for approval, five copies of the post-dredge survey, and the calculations along with sufficient documentation to verify the accuracy of the results.

3.4.2 Extent of Dredge Surveys

The dredge surveys shall cover all the bottom area within the dredge limits of the bottom and side slopes areas. Bottom elevations shall be determined to the nearest tenth of a foot at horizontal intervals of no more than 20 feet.

3.5 FINAL EXAMINATION AND ACCEPTANCE

As soon as practicable and no later than five (5) days after the completion of the entire work, the area will be examined by sounding or sweeping, or both. Remove shoals and lumps by dragging the bottom or by dredging. However, if the bottom is soft and the shoal areas form no material obstruction to navigation, removal may be waived at the discretion of the Contracting Officer. When areas are found to be in satisfactory condition, the work therein will be accepted as complete. Final volume for payment will be subject to deductions for excessive overdepth, dredging outside of authorized areas, or disposal of material in an unauthorized manner.

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1.7 OBSTRUCTION OF WORK AREA

3.5 FINAL EXAMINATION AND ACCEPTANCE