PigsEye_2ndRevisedSection_35_20_23.40_13.pdf

Pigs Eye Islands W912ES20R0002

SECTION TABLE OF CONTENTS

DIVISION 35 - WATERWAY AND MARINE CONSTRUCTION

SECTION 35 20 23.40 13

PLACEMENT OF DREDGED AND STOCKPILED FILL MATERIAL

PART 1 GENERAL

1.1 THE PLANT

1.2 DEFINITIONS

1.2.1 Satisfactory Materials

1.2.2 Sand and Granular

1.2.3 Fine fill and Fines

1.2.4 Temporary Features

1.2.5 Wet, Dry, and Extended Berms

1.2.6 Interior Submerged Bench

1.2.7 Mud Wave

1.2.8 Global Stability Failure

1.3 SUBMITTALS

1.4 EFFLUENT WATER QUALITY

1.5 PIGS EYE LAKE SOIL CONDITIONS AND ANTICIPATED RESPONSE DURING

CONSTRUCTION

1.6 SUGGESTIONS FOR THE WORK AND PLACEMENT PLAN

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Fine Fill

2.1.2 Granular Fill

PART 3 EXECUTION

3.1 GENERAL

3.2 PLACEMENT

3.2.1 Direction of Work

3.2.1.1 Placement of Fine Fill from Access Dredging the Pigs Eye project site

3.2.1.2 Granular Fill Placement from Borrow Sites

3.2.1.2.1 Mud Waves

3.2.1.3 Fine Fill Placement from Borrow Site

3.3 TOLERANCES

3.3.1 Excess Material Outside Tolerances

3.3.2 Temporary Features Removal Tolerances

3.4 FINISHING

3.5 PROTECTION

-- End of Section Table of Contents --

SECTION 35 20 23.40 13 Page 1

SECTION 35 20 23.40 13

PLACEMENT OF DREDGED AND STOCKPILED FILL MATERIAL

PART 1 GENERAL

This section covers filling, grading and other related work for the placement of granular and fine fill obtained from the designated borrow sites, and fine fill obtained from optional access dredging.

1.1 THE PLANT

The plant is defined as all marine and land based equipment necessary to accomplish the work.

The plant shall be subject to the inspection of the Contracting Officer at all times. The Contractor is responsible for supervision and direction of placement operations, including the safe and efficient operation of the plant. The Contractor shall maintain the plant to meet the requirements of the work.

1.2 DEFINITIONS

1.2.1 Satisfactory Materials

Satisfactory materials shall be of a character and quality satisfactory for the purpose intended. Satisfactory material shall be free of ice, snow, frozen earth, trash and debris.

1.2.2 Sand and Granular

For purposes of this contract, granular, granular fill, sand, and sand fill, are the same material and may be used interchangeably on the plans and in the specifications.

1.2.3 Fine fill and Fines

For purposes of this contract, fines, fine fill, and topsoil are the same material and may be used interchangeably on the plans and in the specifications.

1.2.4 Temporary Features

Temporary Features include, but are not limited to, materials for Construction Pads, Bridges, and Plugs. They shall meet the requirements for granular fill. The Contractor shall use granular fill from the designated stockpiles.

1.2.5 Wet, Dry, and Extended Berms

Wet, Dry, and Extended Berms denoted on the plans shall be constructed of granular fill. The Contractor shall use granular fill from the designated stockpiles.

SECTION 35 20 23.40 13 Page 2

1.2.6 Interior Submerged Bench

The Interior Submerged Bench denoted on the plans shall be constructed of granular fill. The Contractor shall use granular fill from the designated stockpiles.

1.2.7 Mud Wave

The term mud wave is used to describe the semi-liquid displacement of soft, unconsolidated foundation soils outward and upward as a result of fill placement.

1.2.8 Global Stability Failure

Global stability failure is a term used to describe a large-scale displacement of soil foundation and fill material that occurs along a clearly defined shear zone. A global stability failure may occur when the shear stresses in the soil foundation induced by a loading (such as fill placement or heavy equipment) exceed the foundation soil shear strength.

1.3 SUBMITTALS

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

submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following shall be submitted in accordance with SECTION 01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Plant Equipment; G, COR

The Contractor shall submit information on all the plant equipment to be used for the placement of all fill materials.

For the equipment used on the islands, the Contractor shall provide the equipment name, weight, the bearing area of the tires or tracks, and the construction season(s) the equipment will be utilized.

Work and Placement Plan; G, COR

Submit a Work and Placement Plan detailing the placement, material handling, and specific methods for all operations including the following:

1. Explanation on how mud-waves will be minimized during granular fill placement. The explanation shall acknowledge that if mud waves are seen above the water surface, the Contractor shall notify the Contracting Officer to evaluate the severity of the impact and potential steps to reduce impacts.

2. A plan that outlines steps to prevent, monitor, and mitigate global stability failures if/when they occur. For suggestions, refer to PART 1 SUGGESTIONS FOR THE WORK AND PLACEMENT PLAN below.

3. The placement and/or disposal of excess material from access dredging material (if applicable).

SECTION 35 20 23.40 13 Page 3

4. For construction pads, bridges, and plugs (optional, where allowed), include proposed location, dimensions, and removal details. In particular, describe how the temporary features will be recovered and where they will be placed based on their content of fines.

5. Show the marine and land staging areas with the proposed location, dimensions, and a schematic layout of each area.

6. Provide a project schedule and include a sequence of work with time line and proposed construction phasing.

7. Show all temporary structures that will be part of this project.

Water Quality Plan; G, COR

The Contractor shall prepare a plan in accordance with Paragraph:

EFFLUENT WATER QUALITY.

Prepare the Work and Placement Plan in conjunction with the Water Quality Plan, and submit all three individual preconstruction submittals as one package for Government review.

1.4 EFFLUENT WATER QUALITY

The Contractor is required to meet the water quality standards as stated in the State of Minnesota SECTION 401 WATER QUALITY CERTIFICATION for dredging and placement of fine fill, whether obtained by mechanical or hydraulic dredging methods.

These permits are located in SECTION 01 57 20.00 13 ENVIRONMENTAL PROTECTION. The Contractor shall submit for approval a Water Quality Plan addressing the requirements of the permits.

The Contractor is responsible for all sampling, testing and reporting of water quality limits as stated in the permits.

Prior to discharging the hydraulic dredging carriage water from the site, the Contractor is required to meet the effluent water quality standards as stated in these permits. Carriage water discharge shall cease immediately during periods when effluent water quality limits and standards are obviously not being achieved.

1.5 PIGS EYE LAKE SOIL CONDITIONS AND ANTICIPATED RESPONSE DURING

CONSTRUCTION

The boring logs included on the plans provide valuable information on the soil foundation conditions. Most borings show very soft compressible soils to a depth of at least 15-20 ft. It is anticipated that during initial granular fill placement, some of the foundation soils will displace laterally and produce mud waves.

Although mud waves are expected to occur during granular fill placement, especially in the first season, minimizing mud waves is desirable from the standpoint of reducing turbidity and managing granular fill quantities.

The foundation soils will consolidate after the first season, increasing the soil foundation shear strengths and allowing the soil foundation to support additional granular fill placement. However, as additional fill is

SECTION 35 20 23.40 13 Page 4 placed there is the potential for global stability failures.

Global stability failures are of greater concern during season two when the Contractor is bringing the granular fill above the waterline and the islands to final grade. A global stability failure has the potential to complicate construction and cause negative impacts on construction operations.

1.6 SUGGESTIONS FOR THE WORK AND PLACEMENT PLAN

Mud Waves: The Work and Placement Plan shall include an explanation on how mud waves may be minimized. Suggestions include, but are not limited to, minimizing the fill placement height and allow time between lifts for the soil foundation material to consolidate and gain strength.

Global Stability Failure: The Work and Placement Plan shall specify steps to 1) prevent, 2) monitor, and 3) mitigate global stability failure if/when it occurs.

Placing granular fill to at least one foot above the water line or to design elevation, whichever is less, in the first construction season will allow consolidation and improve strength gain prior to placing granular fill material to final grade in the second construction season. If construction occurs while the pool is higher than the assumed lower control pool, global stability is improved. The following suggestions are provided for consideration:

1) Prevention of global stability failures may include limiting fill placement height, placing even lifts across the width of the islands, and limiting fill placement and heavy equipment operation near the island edges.

2) Monitoring the project features during construction for signs of an impending global stability failure. Signs include, but are not limited to, large continuous cracks and displacement along the cracks.

3) One suggestion for global stability failure mitigation, in the event that it occurs, is degrading the failing area to prevent further displacement and providing the failed area additional time to consolidate.

Doing so will increase the soil foundation strength such that fill placement and grading can resume.

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Fine Fill

Fine fill for the island construction shall consist of satisfactory material obtained from designated stockpiles at the designated borrow site for fine fill.

Fine fill obtained from optional access dredging shall be handled in accordance with "Placement of Fine Fill from Access Dredging" detailed in Part 3 below.

SECTION 35 20 23.40 13 Page 5

2.1.2 Granular Fill

Granular fill shall consist of satisfactory material obtained from the designated stockpiles at the designated borrow sites for granular fill.

PART 3 EXECUTION

3.1 GENERAL

Placement of fill shall be performed to the lines and grades, and to the limits shown on the drawings.

3.2 PLACEMENT

3.2.1 Direction of Work

The Contracting Officer may require the specific order of placement of fill material to effect a proper disposition that is consistent with environmental constraints and permits. When the parameters of the operation are established, the absence or presence of the Contracting Officer does not relieve the Contractor of the responsibility to maintain a proper placement operation. The Contracting Officer is authorized to stop operations if the placement operation is not meeting permit requirements.

3.2.1.1 Placement of Fine Fill from Access Dredging the Pigs Eye project site

If the Contractor determines it is necessary to access dredge the marine staging area, the Contractor has the option to transport and place the material at the Pine Bend borrow site within the fine material placement area. The maximum capacity of material placed at Pine Bend is 20,000 cyds.

If the Contractor determines it is necessary to access dredge a channel to the islands, there is an option to place the material within the interior (bays) of Islands 5 and 7 per the plans.

Temporary construction plugs must be in place at the islands to contain the hydraulically dredged material during placement. Material placed within the temporarily enclosed bays of the islands shall be placed to encourage a downward deposition slope; north to south within the bay of Island 5, and east to west within the bay of Island 7. Ideally, a deposition gradient where the water is deeper towards the outlet of the bays is desired.

If mechanical access dredging of the channel to the islands is performed and the Contractor determines to place the material within the interior (bays) of Islands 5 and 7, placement of the mechanically dredged material shall be coordinated with the Contracting Officer.

The Contractor is responsible for determining a disposal location for all dredged material that exceeds the capacity or elevation limit designated on the plans for Islands 5 and 7, or that exceeds the 20,000 cyds capacity at the Pine Bend borrow site.

3.2.1.2 Granular Fill Placement from Borrow Sites

The project staging area in Pigs Eye Lake designated on the plans, may be

SECTION 35 20 23.40 13 Page 6 utilized to stage and rehandle granular fill from the borrow sites on the marine plant only. The granular fill may not be stockpiled or rehandled directly in the water.

Refer to PART 1 SUGGESTIONS FOR THE WORK AND PLACEMENT PLAN for suggestions on granular fill placement to minimize mud waves and reduce the potential for global stability failure.

Dry Berms, Wet Berms, and the Submerged Bench: For purposes of tracking short-term settlement, the Contractor shall place the base island granular fill to at least one foot above the water line or to design elevation, whichever is less, in the first construction season and provide the following two surveys for each island in accordance with SECTION 01 71

23.05 13 CONTRACTOR SURVEYS.

1) Post-Season-One for Short-Term Settlement Survey: At the end of construction season one, the Contractor shall complete a post-season-one survey to confirm final grade. This survey must be complete before the winter season.

2) Pre-Season-Two for Short-Term Settlement Survey: Before placing material in construction season two, the Contractor shall complete a survey of the islands placed in season one. This survey must be complete after the winter season and prior to placing any material in season two.

Short-Term Settlement Surveys shall be reviewed by the Contractor and the Contracting Officer to determine the amount of granular needed to top off each island due to short term settlement.

Extended Berms: Granular subgrades shall be constructed to the lines and grades as shown and specified. Once the subgrade is approved by the Contracting officer, and the rock groins are placed in accordance with SECTION 35 31 19.00 13, the extended berm shall be placed as noted in the contract plans.

Once all granular fill is placed and final graded, a Final Granular Grade Survey shall be provided in accordance with SECTION 01 71 23.05 13 CONTRACTOR SURVEYS prior to placing fine fill. Timing of the Final Granular Grade Survey will be one month or less after final grading is complete.

3.2.1.2.1 Mud Waves

The mud wave material is to be left in place. If, at the discretion of the Contracting Officer, the mud wave requires grading, after the granular material placement is complete, spread the mud wave material along the granular material slope forming a smooth transition.

3.2.1.3 Fine Fill Placement from Borrow Site

Fine fill material shall not be placed until the Contractor confirms, through surveys, that design elevation is reached, and it is within tolerances specified in this section. Upon completion and Government acceptance of the island berms and rock groins, the project features are topped with fine fill as noted in the contract plans and in accordance with this section.

SECTION 35 20 23.40 13 Page 7

3.3 TOLERANCES

Unless shown or indicated otherwise, island construction shall conform to the following tolerances:

For the dry berm (including extended berm):

-Top elevations (fine fill) +5 inches -0 inches

-Fine fill layer thickness +4 inches -0 inches

-Granular fill elevations +5 inches -0 inches

For the wet berm:

-Top elevations +0 inches -5 inches

The berm top elevations shall not vary beyond the tolerances indicated irrespective of the other tolerances shown. Tolerances above grade may be revised at locations where, in the opinion of the Contracting Officer, such revisions will not impair the design or appearance of the islands.

3.3.1 Excess Material Outside Tolerances

The Contractor, at the Contractor's own expense shall be responsible to recover/remove material that exceeds the tolerance specified.

3.3.2 Temporary Features Removal Tolerances

Temporary features, such as construction pads, bridges, and plugs required to be removed shall be removed starting from 0.5' to 0.83' (feet) above preconstruction depths.

Granular material recovered from the temporary features must contain less than 10% of fine material for island construction. Recovered granular material with fines content greater than 10% may be used for construction of the sand bench (Islands 5 and 7), the sand floor (Island 6 option), or the material may be placed in the interiors of Islands 5 and 7 to the elevations designated on the plans. If additional capacity is needed for the recovered granular material with fines greater than 10%, placement must be coordinated with the Contracting Officer.

3.4 FINISHING

All fill areas including transition areas shall be reasonably smooth and free from irregular surfaces and suitable for the application of turfing materials. The degree of finish required is that ordinarily obtainable from a blade-dozer with a skilled operator.

3.5 PROTECTION

The Contractor shall protect newly graded areas from traffic damage and erosion. Prior to acceptance, the Contractor shall repair any settlements and repair any areas that have washed away due to any reason. The grades, elevations, and slopes shall be re-establish according to the drawings.

All work shall be conducted in accordance with the environmental protection requirements of the contract.

SECTION 35 20 23.40 13 Page 8

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SECTION 35 20 23.40 13 Page 9

3.2.1.3 Fine Fill Placement from Borrow Site