S01 Amendment 1 - CS 423 Revised.pdf

NRCS-LA Amendment #1 – August 2021 February 2021 South Grand Chenier Marsh Creation (ME-20) 423-1

Construction Specification 423 – Marsh Creation

1. Scope The work shall consist of the excavation and placement of fill required by the drawings and this specification.

2. Material All fill material shall be obtained from the designated marsh creation borrow area (MCBA).

3. Use of excavated material All excavated material shall be placed in the marsh creation areas as shown on the drawings.

The presence of rock, oyster reefs, buried shell, and/or exposed shell are possible, and cannot be excluded with any degree of certainty.

4. Placement Earthfill will not be placed until the placement area has been adequately prepared, inspected and approved by the COR.

5. Disposal of waste materials Any unsuitable excavated materials are designated as waste and shall be disposed of by the Contractor in an environmentally acceptable manner that does not violate local rules and regulations. The method and location of disposal shall be approved by the COR.

6. Borrow excavation The extent and depth of borrow pits within the limits of the designated borrow as shown on the drawings.

7. Measurement and payment For items of work for which specific unit prices are established in the contract, the volume of excavation within the specified pay limits is measured and computed to the nearest cubic yard by methods outlined in section 8 of this specification. Regardless of quantities excavated, the measurement for payment will not extend beyond or outside the specified pay limits. Excavation required because unsuitable conditions result from the Contractor’s improper construction operations is not included for measurement and payment.

The pay limits shall be defined as follows:

• The upper limit shall be the original ground surface of the borrow area as determined by the preconstruction survey.

• The lower and lateral limits shall be the neat lines and grades shown on the drawings or as specified in section 8.

Payment will constitute full compensation for all labor, materials, equipment, and all other items necessary and incidental to the performance of the work.

Compensation for any item of work described in the contract, but not listed in the bid schedule is

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8. Items of work and construction details Items of work to be performed in conformance with this specification and the construction details therefore are:

A. Bid Item 3 - Marsh Creation Fill

1) General

i. This item shall consist of using a cutterhead dredge to excavate marsh creation fill material from the marsh creation borrow area (MCBA) and place the material within the marsh creation area(s) through a dredge pipeline to the extents depicted in the construction drawings. This pay item also includes any other items of work required for performing and completing the marsh creation fill operations.

ii. The Contractor will be allowed to perform marsh creation fill operations within the work limits as shown on the drawings 24 hours a day, 7 days per week.

iii. Reference the Special Provisions of the project specifications for requirements when working near or over pipelines and other utilities.

iv. The Contractor shall notify the COR and CO within 24 hours and no more than 72 hours before the commencement and termination of marsh creation fill operations for each marsh creation area (MCA).

v. All equipment utilized by the Contractor, including the dredge pipeline, shall be located within the work limits, corridors, and routes shown in the construction drawings. Minimal use of marsh buggies or other land-based equipment shall be allowed for pipeline placement and movement outside of the MCAs. Damages to the marsh outside of these areas and or infrastructure resulting from the Contractor’s actions and/or inactions shall be repaired at the Contractor’s expense.

2) Surveys

i. See Construction Specification 7 – Construction Surveys for all surveys applicable to this item of work.

3) Dredge Pipeline

i. It is recommended that before Before excavation operations can commence for a given MCA, the Contractor shall have on-site and in place the required length of dredge pipeline required to reach that MCA’s discharge point that is farthest from the borrow area.

ii. Potential hazards caused by the presence of dredge pipeline or other equipment shall be marked and lighted in a manner that will warn approaching marine vessels of the obstruction(s) and shall conform to the requirements of the United States Coast Guard.

iii. See drawings and the Construction Specification 21, Excavation for details on dredge pipeline at the Hog Bayou Crossing.

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iv. See drawings and Special Provisions for details on dredge pipeline corridor along Lake Price Unit Levee.

4) Cutterhead Dredge

i. The Contractor shall properly size the cutterhead dredge to maintain continuous operations in the Gulf of Mexico under regular conditions and the Work Plan shall the specify size and capacity.

ii. The cutterhead dredge shall be equipped with RTK GPS equipment and continually record the position of the cutterhead.

iii. Dredge shall be equipped with DredgePack, or equivalent, capable of computing the daily dredge volume. Daily dredge volumes must be included in the Contractor’s daily quality control report.

5) Staff Gauges and Settlement Plates

i. The Contractor shall utilize staff gauges to:

• Monitor marsh creation fill operations

• As a guide for material management described in this specification

• To meet tolerance and acceptance criterion described in this specification

• To maintain relatively uniform surface elevations throughout a given

MCA.

ii. The Contractor shall install staff gauges according to the drawings and Construction Specification 93 – Identification Markers or Plaques.

iii. There is a possibility that staff gauges will settle or heave as a result of the pumping activities. See Construction Specification 7 – Construction Surveys for survey requirements.

6) Borrow Area

i. All marsh creation fill material shall be obtained from the MCBA depicted in the construction drawings. Excavation limits within the borrow area are -38.5 feet NAVD 88 GEOID99 with over-excavation tolerance of 3.0 feet to an elevation on -41.5 feet NAVD88 GEOID99.

ii. The cutterhead dredge shall not be anchored, spudded, or in any other way disturb the water bottom outside of the MCBA. If a buffer zone is needed to allow for anchoring inside the MCBA, it should be included in the Work Plan.

7) Material Management

i. The Contractor shall manage the placement of material such that upon reaching the contract volume for a given MCA, the surface elevation of the material within

South Grand Chenier Marsh Creation (ME-20) 423-5 the MCA will be relatively uniform with the highest and lowest elevations having a difference of ≤1.0 foot.

ii. The Contractor shall describe the means and methods for material management in the Work Plan, including but not limited to:

• Dredge discharge point locations and movement

• Dewatering structure management

• And, if deemed necessary by the Contractor, small training dikes dimensions and locations, diffusers or other means to better manage material placement.

iii. One foot (1’) of freeboard between the water surface inside a given MCA and the top elevation of the associated earthen containment dike must be maintained at all times.

iv. One foot (1’) of freeboard shall be applied only between the water surface inside the unconfined MCA’s and the top elevation of the Price Lake Unit Levee.

v. If the Contractor is not allowing sufficient time for the MCA to dewater for the sediment to settle out of suspension, the COR may periodically require the Contractor to cease marsh creation fill operations to allow the MCA to dewater or for the sediment to settle out of suspension. All costs incurred by the Contractor for ceasing operations for the purpose of allowing sediment to settle out shall be absorbed by the Contractor with no additional cost to the Government.

8) Volume

i. Marsh creation fill material will be placed in each of the MCAs depicted in the construction drawings, utilizing a pre-determined cut volume. Each confined MCA shall be surrounded by earthen containment dikes.

ii. These volumes are a pre-determined cut quantity to be removed from the MCBA and placed in each MCA. The Contractor will be required to dredge the specified volume of marsh creation fill material into the corresponding MCA.

iii. DredgePack volumes will be used to monitor cumulative marsh creation fill volumes dredged and placed into each MCA. Cumulative daily volumes will be compared to progress MCBA surveys for quality assurance purposes.

iv. The COR and inspector shall be notified once the Contractor determines that the contract volume has been achieved for a given MCA.

v. Below are the required cut volumes to achieve the design fill template.

• East Confined MCA: 601,259 cubic yards

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• West Confined MCA: 255,347 cubic yards

• Unconfined MCA: 18,536 cubic yards

9) Spillage

i. In the event that overtopping or failure of the earthen containment dikes or discharge structures occurs, the Contractor shall cease dredging activities in the affected area until the situation has been corrected as concurred by the COR.

After such an event, the Contractor shall provide an estimated volume of material lost to the COR for review and concurrence. This volume of material will be at the Contractor’s expense and will not count toward the total volume placed within any given MCA. The Contractor shall be legally and financially responsible for any penalties, fines, mitigation requirements, etc. resulting from the overtopping or failure event.

ii. If excessive, repetitive, or complete failure of the earthen containment dikes occurs (as determined by the CO or COR), NRCS may terminate placement of marsh creation fill material into the MCA(s) where the failure occurred and direct the Contractor to place material into another area.

iii. The Contractor shall take the necessary actions to prevent excessive leakage of the dredge pipe as concurred by the COR. The joints shall be constructed to preclude spillage and leakage.

iv. If the dredge pipe fails for any reason during marsh creation fill operations, the Contractor shall immediately cease dredging until the pipe failure is repaired and proper function of the dredge pipe is restored as concurred by the COR. The estimated quantity of material lost, as concurred by the COR, shall be at the Contractor’s expense and will not count toward the total volume placed within any given MCA. The Contractor shall be legally and financially responsible for any penalties, fines, mitigation requirements, etc. resulting from any leaks or unpermitted discharges.

10) Tolerances and Acceptance

i. Upon notification from the Contractor that marsh creation fill operations have been completed for any given MCA and is concurred by the COR, NRCS shall perform the final as-built MCBA survey within 72 hours of notification.

ii. All surveys of the MCAs performed by the Contractor shall conform to Construction Specification 7 – Construction Surveys and shall be submitted to the COR for acceptance.

iii. The fill elevation tolerance for each MCA shall be within 1.0 ft measured from the highest to the lowest elevation based on the MCA as-built surveys. The intent of this specification is to achieve a relatively uniform average fill elevation throughout each MCA.

iv. Summary of acceptance criteria for a MCA:

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• Specified volume must be pumped into each MCA, which will be determined by DredgePack volumesand/or MCBA survey;

• Fill elevation must be relatively uniform as described in (iii) above, which will be determined by the Contractor’s MCA as-built survey;

• Concurrence from the COR on (a) and (b) above.

v. If an MCA is outside of tolerance, the Contractor may be required to dredge additional material in order to meet the tolerance at no expense to the government.

11) Progress Measurement and Payment

i. Measurement for progress payments shall be performed by the Contractor in accordance with Construction Specification 7 – Construction Surveys of this contract and in accordance with the Contractor’s approved Work Plan.

ii. All measurements and computational data utilized to determine progress payment quantities shall be provided to the COR a minimum of 7 days prior to requesting payment. Excavation occurring beyond the limits depicted in the construction drawings shall be at the Contractor’s expense and will not be compensated by the government.

12) Final Measurement and Payment

i. The final quantities for payment shall be determined by NRCS. Surveys for this measurement shall be as defined in Construction Specification 7 – Construction Surveys.

ii. NRCS pre- and post-excavation surveys of the MCBA will be used to compute quantities for final payment. Payment will be made only for those portions of the MCBA where excavation has occurred.

iii. In areas limited by side slopes, payment will be made to the elevations defined by the slopes. Excavation occurring beyond the limits depicted in the construction drawings shall be at the Contractor’s expense and will not be compensated by the government.

iv. Payment will be made at the contract unit price for material excavated down to an elevation of -38.5’ NAVD 88. Progress payment shall be based on the quantity measured by the Contractor and calculated in accordance with the previous paragraph. Final payment will be made at the contract unit price for the final quantity measured by NRCS as prescribed above. Such payment will constitute full compensation for all labor, equipment, material, and Subsidiary Items including, Pollution Control and Contractor Quality Control.