31_23_00_Amendment_0004.pdf

Boardman Dam Removal and River Restoration

SECTION TABLE OF CONTENTS

DIVISION 31 - EARTHWORK

SECTION 31 23 00

EARTHWORK

PART 1 GENERAL

1.1 SUMMARY

1.2 RELATED WORK SPECIFIED ELSEWHERE

1.3 REFERENCES

1.4 SUBMITTALS

1.5 PROJECT CONDITIONS

1.6 PROTECTION OF FACILITIES AND SITE

1.7 DEFINITIONS

1.8 SOURCE QUALITY CONTROL TESTING

1.9 MANAGEMENT OF EXCAVATED MATERIALS

PART 2 PRODUCTS

2.1 COMMON BORROW

2.2 GRANULAR BORROW

2.3 NATIVE SUBSTRATE

2.4 AGGREGATE BASE

2.5 BULK BAGS

2.6 OIL ABSORBENT BOOMS

PART 3 EXECUTION

3.1 INSPECTION

3.2 EXCAVATION

3.3 STABILITY OF EXCAVATIONS

3.4 SOIL/MATERIAL HANDLING AND STORAGE

3.5 COLD WEATHER PROTECTION

3.6 CLOSING ABANDONED UNDERGROUND UTILITIES

3.7 GRADING

3.8 BACKFILL AND FILL PLACEMENT AND COMPACTION

3.9 FIELD QUALITY CONTROL TESTINGS

3.10 EARTHWORK TOLERANCES

3.11 MAINTENANCE

3.12 DISPOSAL OF EXCESS AND WASTE MATERIALS

-- End of Section Table of Contents --

SECTION 31 23 00 Page 1

SECTION 31 23 00

EARTHWORK

PART 1 GENERAL

1.1 SUMMARY

A. This Section covers excavation, filling/backfilling, compaction, grading and temporary access for restoration of the Boardman River channel and floodplain as well as dam breaching and spoils pile grading. Cass Road embankment is not coverd under this section. Major work elements include but are not limited to:

1. Boardman River Restoration

a. Excavation of soil and sediment to restore the relic river channel.

b. Construction and maintenance of Sediment Traps for sediment management.

c. Placement of cut material in spoil areas noted.

d. Removal of existing vegetation within the footprint of the channel alignment.

e. Establishment and maintenance of access routes and river crossings as needed to support earthwork.

f. Habitat enhancement excavation.

2. Boardman Impoundment Dewatering

a. Excavation of Auxiliary Spillway.

b. Excavation and grading of Auxiliary Spillway Stilling Basin.

c. Excavation and grading of Siphon Energy Dissipation Structure.

d. Excavation and grading of temporary river channel from earthen dam embankment downstream to Sabin Pond.

e. Excavation of dredged channel in front of Auxiliary Spillway.

f. Placement of cut material in temporary location as indicated on drawings and later fill and grading of existing dam intake channel.

3. Boardman Dam Breaching

a. Excavation of earthen dam material in area of proposed restored river channel.

4. Bulk Bags

a. Installation of temporary Bulk bag Cofferdam in the final breach step upstream of the earthen plug.

B. Contractor is advised that excavation for restoration of the Boardman River channel and floodplain from the dam to the limits of work will proceed with significant construction assistance from the COR as well as the A/E Designer of Record. Typical lines and grades are shown on the drawings to set approximate design topography and limits, and to quantify mass cut /fill volumes. Actual final line, grades and dimensions will deviate to mimic natural river features. Typical deviations include deeper bed elevations in pools with a narrower channel section and wider channel sections with shallow beds in riffle and run sections, and floodplain elevations and widths which vary from those depicted on the plans.

Specific locations of these features (pools, riffles, runs) will be verified as excavation encounters the proposed grade and/or the pre-dam channel surface and features such as historical stumps, at which point field adjustment may occur.

C. Control of surface water run-off and run-on during construction, shall be in accordance with Section 31 23 19 Dewatering.

SECTION 31 23 00 Page 2

1.2 RELATED WORK SPECIFIED ELSEWHERE

A. Section 01 11 00: Summary of Work

B. Section 01 33 00: Submittal Procedures

C. Section 02 41 16: Structure Demolition

D. Section 02 42 09: Waste Removal and Handling

D. Section 31 23 19: Dewatering

E. Section 31 40 00: Slope Protection and Erosion Control

F. Section 31 39 00: Large Wood - Habitat

1.3 REFERENCES

The publications listed below form a part of this Section to the extent referenced. The most recent issue of each publication shall apply, unless otherwise noted. The publications are referred to in the text by the basic designation only.

ASTM INTERNATIONAL (ASTM)

ASTM C136 Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates

ASTM D422 Standard Test Method for Particle-Size Analysis of Soils

ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3)

ASTM D2487 Standard Classification of Soils for Engineering Purposes (Unified Soil Classification System)

ASTM D3740 (2012a) Standard Practice for Minimum Requirements for Agencies Engaged in the Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction

ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

ASTM D6938 Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)

SECTION 31 23 00 Page 3

Michigan Department of Transportation (MDOT)

MDOT MDOT, Special Provision for Embankment, CIP, Special.

1.4 SUBMITTALS

A. The Contractor shall submit the following items to the Engineer in accordance with Section 01 33 00 Submittal Procedures:

SD-01 Preconstruction Submittals

1. Excavation and backfill plan, including means, methods, sequencing equipment, and schedule for any work that involves excavation of soils and sediment of the site and backfill of soils/sediments, whether in spoils areas or as permanent backfill in the existing spillway channel that will be filled and decommissioned by the project. The plan shall include provisions for salvage and management of native substrate and soil for reuse in project construction..

a. Submit as a component of the Work Plan, as described in Section 01

11 00 Summary of Work.

2. Sediment Excavation Sequencing Plan; G-DR

a. A preliminary sediment excavation sequencing plan is included in the drawings. The Contractor shall submit to the COR for approval a revised plan that includes description of the planned approach to excavation and disposal of the impounded reservoir sediments, including description of means and methods, equipment to be used, and sequencing with other work items such as drawdown of the headpond and dam demolition.

b. Temporary Stream Crossing Plan Plans for access and temporary stream crossings shall be documented. Crossings must maintain river flow and may be wet or dry depending on their frequency of useand must maintain the access alignment above or outside of the active flowing stream, unless otherwise approved by COR. Provisions for temporary stream crossings shall be of the Contractors own design and construction, comply with all applicable regulations and permits, and provide a level of service that facilitates completion of the work. Boardman River flow data is available on Drawing sheet T-1.2.

SD-03 Product Data

3. Borrow Source(s):

a. The Contractor shall provide the proposed source(s) for borrow materials prior to initiation of work.

b. Laboratory testing data shall be provided.

4. Decontamination Pad:

a. Submit two (2) copies of the following:

(1). Details for the decontamination pad, including location and materials.

SD-06 Test Reports

5. Quality Control Testing Laboratory:

a. The name and qualifications of an independent third-party commercial testing laboratory to be used for borrow source testing (geotechnical) and in-place soil/construction materials testing shall be submitted as soon as possible, but no later than 7 days following notice to proceed.

b. The proposed geotechnical laboratory shall meet the requirements

SECTION 31 23 00 Page 4 of ASTM D3740.

6. Analytical Testing Laboratory:

a. The name and qualifications of an independent third-party commercial testing laboratory to be used for contaminated soil testing (analytical) shall be submitted as soon as possible, but no later than 7 days following notice to proceed.

7. Quality Control Test Reports:

a. Submit two copies of the following reports:

(1). Geotechnical laboratory test reports for select borrow source materials.

(2). Field in-place density (compaction) test reports of material for backfill within the new channel at and adjacent to the powerhouse.

1.5 PROJECT CONDITIONS

A. Site Information:

1. Survey data provided on topographic (surface and bathymetric) conditions are not intended as representations or warranties of accuracy or continuity between data points. It is expressly understood that neither the Owner, engineer, nor the government will be responsible for interpretations or conclusions drawn there from by Contractor. Data are made available for the convenience and information of the Contractor.

2. Grades and Lines provided for restoration are provided as guidance only and are expected to be adapted during project construction. Areas for field adjustment are those areas of the floodplain and below the bankfull elevation of the river channel which will be adapted to pre-dam features such as relic stumps and channel indicators and the final grades and volume of noted spoils areas.

3. Work will occur within a dynamic riverine environment with the probability of significant changes to site conditions during the project. Flooding, groundwater drainage, and drawdown of the impoundment will require diligent attention to site conditions on a daily basis.

4. Subsurface information is provided for the Contractor in section 02 30 00 Geotechnical Data. Subsurface data are not intended as representations or warranties of accuracy of subsurface conditions.

It is expressly understood that neither the government, nor the engineer will be responsible for interpretations or conclusions drawn there from by Contractor. Data are made available for the convenience and information of the Contractor. Additional test borings and other exploratory operations may be made by Contractor.

B. Existing Utilities:

1. The Contractor shall locate in the field existing underground utilities in the areas of work. If utilities are to remain in place, provide adequate means of protection during earthwork operations. Cap or fill all abandoned pipes and conduits encountered during construction with grout.

2. Should uncharted, or incorrectly charted, piping or other utilities be encountered during excavation, consult the utility owner immediately for directions. Cooperate with the utility companies in keeping respective services in operation. Contractor shall repair damaged utilities to satisfaction of the utility owner.

C. Use of Explosives:

SECTION 31 23 00 Page 5

1. Use of explosives shall not be allowed.

1.6 PROTECTION OF FACILITIES AND SITE

A. The Contractor shall protect existing site features and structures to remain, utilities, trees, vegetation, and drainage ways which are to remain. The Contractor shall employ similar precautions, as necessary, to prevent damage to or pollution of adjoining properties or rights of way.

B. The Contractor shall use the necessary precautions to prevent damage to pipes, conduits, and other underground facilities that are to remain.

1. At a minimum, the Contractor shall notify MISS DIG System, Inc. in advance of any subsurface activities, including but not limited to excavation, trenching, grading, pavement milling, saw cutting, fence post installation, etc.

C. The Contractor shall repair and/or replace, at no additional cost, any site features, utilities, or property damaged by its employees or subcontractors during construction.

D. Protection of Persons and Property:

1. Barricade and mark open excavations occurring as part of this work in accordance with applicable standards.

2. Protect structures, utilities, sidewalks, pavements, and other facilities designated to remain from damage caused by settlement, lateral movement, undermining, washout, and other hazards created by earthwork operations and truck traffic.

E. Any equipment operating within the river shall utilize a non-petroleum based hydraulic fluid. Hydraulic fluid shall be Chevron Clarity or approved equivalent.

1.7 DEFINITIONS

A. Contaminated Soils/Sediments:

1. Contaminated soils/sediments are not anticipated to be encountered during the work. Contaminants soils/sediments are those materials that become contaminated as a result of the work due to fuel or hydraulic spills.

B. Unsatisfactory Soil/Material:

1. Unsatisfactory soils/materials include but are not limited to peat and/or highly organic soils (classified as OL, OH, or Pt by ASTM D2487 ), stumps/brush, trash, refuse, debris, frozen soils, contaminated soils that do not meet site re-use criteria, soils containing materials greater than the allowable size (see below), saturated soils, fine-grained soils above their liquid limit at the time of compaction, and soils which are either too wet or too dry to compact, as determined by the Government Representative.

C. Construction Demolition Debris:

1. Demolition debris consists of concrete, brick, wood, metal, glass, any other deleterious former construction product.

D. Satisfactory Soil/Material:

1. Satisfactory soils/materials shall meet the requirements specified in this Section, and shall be used in areas as shown on the Construction Drawings or as directed by the COR.

SECTION 31 23 00 Page 6

E. Cohesionless and Cohesive Soils:

1. Cohesionless soils include gravels, sand-gravel mixtures, sands, and gravelly-sands, classified as GW, GP, SW, or SP by the Unified Soil Classification System (ASTM D2487).

2. Cohesive soils include clayey gravels, sand-clay mixtures, clayey sands, clays, and silts, classified as GC, SC, CL, CH, ML, or MH by the Unified Soil Classification System (ASTM D 2487). Soils classified as GM and SM will be identified as cohesionless only when the fines are determined to be non-plastic.

3. Testing required for the classification of soil shall be in accordance with ASTM D4318, ASTM C136, and ASTM D422.

F. Degree of Compaction:

1. Degree of compaction (percent compaction) required is expressed as a percentage of the maximum dry density, at the optimum moisture content. 2. The maximum dry density and optimum moisture content shall be obtained by the test procedure presented in ASTM D1557 (Modified Proctor).

G. Organic Soil:

1. Excavated impoundment material having a visibly darker coloration indicating the presence of organic materials within the matrix, but also contains a substantial proportion of mineral soil.

H. Sand Soil:

1. Excavated impoundment material composed completely of sand or other coarse particles without any visible indication of organic material within the matrix.

I. Native Substrate:

1. Excavated impoundment material derived from stream or glacial sources that is typically rounded and may include the following in varying proportions: sand, gravel, cobble and boulders.

J. Pilot Channel:

1. The area of cut required to expose the pre-dam channel bed and banks only, without any excavation of the floodplain areas beyond the bank edges. Daylight slopes would be 2:1.

K. Floodplain:

1. The area lying adjacent to and above the top of bank of the main river channel.

L. River Channel:

1. The bed and banks that contain normal flow of the river

M. Pre-Dam Channel

1. The Boardman River channel that existed before the dam was built

N. Bankfull Channel:

1. The channel bed and banks lying below the top of bank elevation also considered the floodplain elevation. This is the channel that carries normal water flow.

1.8 SOURCE QUALITY CONTROL TESTING

A. Borrow source testing shall be conducted on all soil materials proposed for construction. The Contractor shall subcontract the services

SECTION 31 23 00 Page 7 of an independent, third-party geotechnical laboratory testing and inspection service to perform testing of any borrow material to be furnished by the Contractor as specified below.

1. Common Borrow:

Test Methodology1 No. of Tests2

a. Particle-Size Analysis ASTM D 422 3 tests min (combined sieve/hydrometer)

b. Atterberg Limits ASTM D 4318 3 tests min

c. Proctor (Modified) ASTM D 1557 3 tests min

2. Granular Borrow:

Test Methodology1 No. of Tests2

a. Particle-Size Analysis ASTM D 422 3 tests min b Proctor (Modified) ASTM D 1557 3 tests min

3. Aggregate Base:

Test Methodology1 No. of Tests2

a. Particle-Size Analysis ASTM D 422 3 tests min

b. Proctor (Modified) ASTM D 1557 3 tests min

Notes:

1. Other testing methods may be considered acceptable, based on prior approval of the Government Contracting Officer.

2. Number of tests shall be as listed, at any change in borrow source.

1.9 MANAGEMENT OF EXCAVATED MATERIALS

A. Some or all of the soil that is excavated to support Powerhouse demolition or embankment regrading may be reclaimed for re-use as backfill to achieve final grades provided it meets the requirements of Common Borrow, as determined by the Contractor and approved by the Government Representative.

B. The Contractor shall determine if excavated soil/sediment that appears to be contaminated requires testing and characterization prior to off-site disposal or re-use.

C. The Contractor shall ensure required waste characterization has been completed to the satisfaction of the pre-designated treatment, storage, and/or disposal facility (TSDF) prior to transporting material for off-site disposal for any contaminated soils/sediments.

D. Waste removal, handling, and management shall be in accordance with Section 02 42 09 Waste Removal and Handling.

E. Transportation and disposal of excavated materials that require off-site disposal shall be in accordance with Section 02 42 09 Waste Removal and Handling.

PART 2 PRODUCTS

2.1 COMMON BORROW

A. Common Borrow shall be used, as necessary, to supplement excavated soils to be placed to achieve final grades of the dam embankment as shown

SECTION 31 23 00 Page 8 on the drawings.

B. Common Borrow shall consist of earth, suitable for embankment construction, and shall be free from frozen materials, perishable rubbish, peat, and other Unsatisfactory Soil/Material. Common Borrow shall meet the following gradation requirements:

Sieve Size Percent Passing by Weight

3 inch 100

1 inch 90-100

No. 4 50-100

No. 40 20-75

No. 200 0-25

C. Common Borrow shall be of such a nature and character that it can be compacted to the specified density (Subsection 3.8).

D. The moisture content shall be sufficient to provide the required compaction in subsection 3.8. In no case shall the moisture content exceed 4% above optimum, which shall be determined in accordance with ASTM D1557.

E. Common Borrow, whether from off-site borrow or re-claimed material from the project site, must meet soil use and re-use criteria specified in subsection 1.7.D of this Section.

2.2 GRANULAR BORROW

A. Granular Borrow shall be used to backfill the channel at the powerhouse and dam as shown on the Drawings.

B. Granular Borrow shall consist of earth, suitable for embankment construction, and shall be free from frozen materials, perishable rubbish, peat, and other Unsatisfactory Soil/Material. Granular Borrow shall meet the following gradation requirements:

Sieve Size Percent Passing by Weight

3 inch 100

1 inch 65-100

No. 4 35-85

No. 200 0-5

May be obtained as reclaimed material on site if it meets the material

SECTION 31 23 00 Page 9 gradation requirements.

2.3 NATIVE SUBSTRATE

A. Excavated impoundment material derived from stream or glacial sources that is typically rounded and may include the following in varying proportions: sand, gravel, cobble and boulders. If previously reviewed and approved by the COR as suitable, salvaged native substrate may be used as an element of the stabilization of Tributary 1, or as a component of the substrate mixture for stream bed construction shown on the Drawings through the former dam embankment or in the vicinity of the Cass Road bridge.

2.4 AGGREGATE BASE

A. Aggregate Base shall be used as borrow fill for reinforcement or surfacing of temporary access roads and as temporary fill for installation of temporary culverts along the temporary access road.

B. MDOT 21AA shall be used. Refer to MDOT Specification Division 9 Section 902: Aggregate

2.5 BULK BAGS

A. Bulk bags shall be constructed from woven polypropylene fabric. Bulk Bag fabrics shall be tested per ASTM G-154 Light/Water Exposure of Nonmetallic Materials and ASTM D-4329 Light/Water Exposure of Plastics for UV and Water resistance. Bulk Bags shall have a minimum capacity of 3000 pounds and have a closed top. Bulk Bags shall be a Spread Strap container with 28-inch by 28-inch base as manufactured by Bag Corp, or approved equal.

2.6 OIL ABSORBENT BOOMS

A. Shall be 5-inch, minimum, diameter and constructed of an outer mesh that contains oil absorbent filler material.

B. Shall be capable of absorbing all hydrocarbons including, oil, gasoline, diesel and lubricating oils.

C. Shall not sink when saturated with oil.

D. Shall be of a length that to span the active flow of the river

PART 3 EXECUTION

3.1 INSPECTION

A. Examine the areas and conditions under which excavating, filling, and grading are to be performed and notify the COR, in writing, of conditions detrimental to the proper and timely completion of the Work. Do not proceed with the Work until unsatisfactory conditions have been corrected in an acceptable manner.

SECTION 31 23 00 Page 10

3.2 EXCAVATION

A. General excavation consists of removal, handling/management, placement or disposal of material encountered during the following Site activities:

1. Boardman River Restoration

2. Boardman Dam Removal

B. Excavation of Impoundment Sediment:

1. Ensure all controls are available or in place.

2. An average channel and floodplain template used to establish grading shown on the drawings. It consists of a 47 foot bottom channel width, bank height ranging from 2.8 to 3.0 feet and 40 feet (total) floodplain width - divided unevenly along and adjacent to the left and right sides of the channel as shown on the Drawings. Cut slopes along channel banks are 2H:1V (horizontal to vertical); all other cut and fill slopes are 3H:1V (horizontal to vertical) unless steeper native slopes are encountered. The final channel geometry will vary from the average section, which will be adapted during construction with the assistance of the Government Representative. Adjustments will be made for indications of the pre-dam channel and floodplain, such as pre-dam river bed and the position of relic stumps indicating channel and floodplain positions and elevations.

3. Approximate excavation depths and dimensions are provided on the Drawings. The Engineer will provide oversight to interpret field conditions uncovered during excavation. Depth of excavation should be guided by elevations noted in the Drawings as well as the presence of stumps or gravels indicating the position and elevation of the pre-dam river channel. Excavation shall not proceed below coarse bed material (gravel) or tree roots without the approval of the COR as these may be indicators of the pre-dam channel and floodplain areas.

4. Excavated spoils should be cast onto the adjacent floodplain then moved to disposal areas or spoiled directly in spoils areas if feasible. The top surface of all spoil areas shall be covered with a soil mix containing a minimul 5% organic soil with a minimum of 6" layer after consolidation. No imported material may be required to meet this condition.

5. Excavate channels to the extent practical along the proposed alignment outside of the current river location before drawdown of the impoundment. If necessary, priority should be placed on vertical excavation to expose the channel bed before excavating to expose the floodplain. Extent of excavation that may be completed before drawdown of the headpond will be determined by site requirement.

6. During drawdown ensure that sediment transported by the river is collected in sediment traps. Preliminary locations of sediment traps are shown on the Drawings. Locations shall be verified by the Contractor's Sediment Excavation Sequencing Plan. More sediment traps than shown on the drawings may be required to facilitate the work as in site conditions dictate. Sediment traps may require frequent cleanout until sediment delivery decreases. Excavation shall proceed in an upstream to downstream direction.

7. Excavation below station 210+00 and to the dam will be determined by the Government Representative as the surface is revealed following drawdown. Determination of this area of work will take no less than 3 working days (excluding weekends). Average channel dimensions in this section will be guided by the average channel template section.

Excavation of this section will proceed in an upstream to downstream direction.

8. Channel excavation near the dam embankment shall remove known and

SECTION 31 23 00 Page 11 accumulated sediment to the maximum extent practical before removing the final barrier to flow at the dam.

9. Removal of obstructions and undesirable materials in excavation includes, but is not necessarily limited to, removal of old foundations, existing construction, logs, riprap, and any other materials which may be concealed beneath the waterline or present grade, as required to perform the Work as indicated on the Drawings and in the Specifications. If undesirable material and obstructions are encountered during excavation, remove material and replace with consultation as directed by the Government Representative.

10. Impounded sediments to be excavated may consist of cobble, gravel, sand, silts, clays and organic material. Varying soil moisture contents will be encountered during the excavation. The Contractor shall be equipped to handle excavation with moisture content ranging from dry to very wet during excavation including handling, loading, transport and disposal.

11. The top lift placed in all spoils areas shall include a soil mix with a minimum 5% organic soil make up to a thickness of 6 inches to promote vegetation growth as described above. Excavated material that is classified as organic soil may be stockpiled and placed as the top lift in spoils areas. The Contractor may instead import organic soil from a prior approved source to meet this requirement if deemed more efficient and economical. No extra compensation will be made if the Contractor chooses to import organic soil instead of salvage organic soil from onsite sources for this purpose.

12. Excavated materials not earmarked for salvage, stockpile and reuse shall be disposed at the excavation spoils piles designated on the Drawings, and unless otherwise indicated in the field by the COR. The Contractor shall spread or shape the spoils at the disposal site as necessary to complete the work and to result in landforms with variable side slopes, resulting in landforms that are natural in appearance and character.

13. Do not carry excavations beyond that shown on the Drawings except as directed by COR. No extra compensation will be made to Contractor for excavation beyond the grades shown on the Drawings without prior approval and modification by the Contracting Officer.

14. The Contractor is required to design, furnish and maintain all temporary stream crossings as necessary to complete the work.

Temporary crossings shall be removed completely at the end of and remove them from river following construction.

15. The Contractor is required to completely remove Aggregate Base used for the temporary crossings at the end of construction.

C. Sediment traps shall be excavated at locations shown on Drawings or as approved by the COR. Traps shall be in place prior to the start of drawdown, unless covered by water in which case they will be constructed when headpond elevations allow access.

1. Sediment Traps shall induce a pool of water at a minimum 3 foot deep by 120 foot long by 55 feet wide.

2. Pool depth may be maintained by using Bulk Bags, or equal, as a weir to control optimal water depth.

3. Monitoring shall ensure flow does not erode around Bulk Bags and compromise water control.

4. Traps shall not be excavated lower than the pre-dam channel elevation unless approved by the COR. If excavation below pre-dam or proposed grades as indicated in the Drawings occurs, coarse material shall be stockpiled and replaced to original grades following construction.

5. Sediment traps shall be maintained by periodically removing accumulated sediment. Sediment traps shall be maintained as required

SECTION 31 23 00 Page 12 to reduce the transport of sediment within the project area.

6. Sediment spoils excavated during sediment trap construction or maintenance shall be placed in spoil areas as shown on the Drawings.

D. Construction of Spoil Areas:

1. No material shall be spoiled outside of the areas noted on the

Drawings without approval by the COR.

2. Construct embankments and fills at locations and to the approximate lines and grades indicated or as directed by Government Representative, to result in landforms that are natural in appearance and character.

3. Vegetation material removed from excavation areas or found in place may be buried in spoils areas with COR approval.

4. Spoils areas must be fully contained within the limits indicated in the Drawing to avoid inadvertent wetland impacts. Do not deviate from the limits shown without prior approval by the COR.

5. Spoil areas grades may be adjusted in the field by the Government Representative to maximize material handling efficiency and to result in naturalized landforms.

6. Maximum slopes of Spoil areas must not exceed 3H:1V.

E. Habitat Enhancement Excavation by Dig and Pitch Method:

1. Following completion of dam removal and major excavation within the impoundment to the lines and grades shown on the drawings and/or as adapted by the Engineer, additional excavation work will be required to re-establish habitat and geomorphic features in the channel (pools, bars and riffles) as shown in typical details on the Drawings or as indicated by the Engineer.

2. Habitat Enhancement Excavation will follow a "fit in the field" dig and pitch method with the Government Representative working directly with the Contractor to determine the final channel bed lines and grades. This work primarily consists of digging pools in the channel bed, using the excavated material to create bars within the channel, and locally steepening channel areas to create riffles, all at locations that are in relationship to the planform of the channel.

3. The work will generally result in balance cut and fill in the streambed. Spoils areas shall be used to waste material, as required.

F. Embankment Dam Excavation:

1. The Contractor shall excavate to the vertical and horizontal limits defined on the Construction Drawings to facilitate the demolition of the powerhouse and removal of portions of the embankment dam to form the new river channel.

2. Permanent stable excavation slopes shall be maintained as describe on the Drawings and in subsection 3.3 of this Section.

3. Excavated soils shall be stockpiled on-site and re-used as appropriate to achieve final grading of the channel at the embankment dam provided that the soils meet backfill criteria.

G. Boardman Dam Breaching:

1. The contractor shall excavate earthen dam material in area of proposed restored river channel to the vertical and horizontal limits defined on the Drawings.

2. Based on geotechnical evaluation (02 30 00 - Geotechnical Data) excavated material could be used for Cass Road Embankment, CIP (32 12 16 - Cass Road Specification). Contractor to verify material meets the MDOT Class II criteria.

H. Bulk Bags

1. Bulk Bags are to be filled with clean sandy material in the dry and

SECTION 31 23 00 Page 13 then placed per manufacture’s recommendations in locations indicated on the plans or as directed by the Engineer.

2. Sandy material from Bulk Bags can be used as fill material in areas shown on the plans or as directed by the Engineer. The Bulk Bags will remain as property of the Contractor and shall be disposed of per section 3.13 DISPOSAL OF SURPLUS AND WASTE MATERIALS.

3.3 STABILITY OF EXCAVATIONS

A. Slope sides of excavations shall comply with applicable codes and ordinances. Shore and brace where sloping is not possible because of space restrictions, stability of material excavated, or where protection of adjacent structures is required.

B. Maintain sides and slopes of excavations in a safe condition until completion of backfilling, or longer if specified or directed by the COR.

C. The Contractor shall barricade areas within the influence of excavation to preclude access or vehicle traffic/operations.

3.4 SOIL/MATERIAL HANDLING AND STORAGE

A. During daily excavation activities, locate and retain soil materials away from edge of excavations. All temporary/daily stockpiles shall be maintained a sufficient distance from the excavation to prevent surcharge loading of the slope and to provide for stability of the slope.

B. During excavation, demolition debris shall be segregated from contaminated soil/sediment that must be disposed of off-site, and from reclaimed soil that meets site Common Borrow specification guidelines.

All waste soils and materials shall be handled in accordance with Section 02 42 09 Waste Removal and Handling.

C. The Contractor shall direct load and unload soil/materials into and from trucks to the extent possible to minimize on-site storage of soil/materials.

D. Designated storage/stockpile areas shall be established for the following soils/materials, as required:

1. Demolition debris;

2. Reclaimed soil for re-use as material for Common Borrow backfill;

3. Imported borrow soil and aggregate that meets criteria for use on site; and

4. Soil and sediment that shall be placed in spoils areas on site.

E. The Contractor shall place, grade, and shape stockpiles to provide for proper drainage. Stockpiles shall incorporate appropriate erosion and sedimentation controls in accordance with Section 31 40 00 Slope Protection and Erosion Control to prevent the off-site migration of sediments. Stockpiles shall be located, shaped, and managed so as to prevent run-on from entering the stockpile and run-off from entering the excavation.

F. Dispose of excess soil and sediment as specified herein at spoils areas, and dispose of contaminated material and waste soil/materials as specified herein and in accordance with Section 02 42 09 Waste Removal and Handling.

SECTION 31 23 00 Page 14

3.5 COLD WEATHER PROTECTION

A. Protect excavation bottoms against freezing if filling is to be performed on that surface when atmospheric temperature is less than 35 F.

3.6 CLOSING ABANDONED UNDERGROUND UTILITIES

A. Close open ends of abandoned underground utilities, indicated to remain, permanently with closures sufficiently strong to withstand pressures which may result after closing.

B. Close open ends of metallic conduit and pipe with threaded galvanized metal caps or plastic plugs, or other suitable method for the type of material and size of pipe. Do not use wood plugs.

C. Close open ends of concrete and masonry utilities with not less than 8-inch thick brick masonry bulkheads, constructed to completely fill the opening.

1. Wet brick before laying. Lay brick in mortar so as to form a full bed with ends and side joints in one operation. Joints shall not be more than 3/8 inch wide. Protect fresh masonry from freezing or from rapid drying, as necessary, and maintain protection until mortar has set.

3.7 GRADING

A. The Contractor shall uniformly grade areas within the limits of work for the channel, floodplain embankment regrading, and spoils areas.

B. At the dam embankment, smooth finished surface within 0.5 foot (horizontal and vertical)of design lines and grades, compact with uniform levels or slopes between points where elevations are shown, or between such points and existing grades. Finish surfaces to be free from irregular surface changes.

C. In the remaining spoils areas rough and irregular surfaces are acceptable, provided a stable fill is constructed.

D. Channel dimensions are expected to change during construction and will be guided by the Government Representative. Grading above the bankfull elevation of the channel is expected to incur less adjustment, but may be adapted to pre-dam indicators.

E. Finished slopes along the daylight edge of the floodplain and within the spoils areas are critical to maintaining the stability of material.

When completed, the average plane of the slopes shall conform to the slopes indicated on the Drawings, and no point on the completed slopes shall vary from the designated plane by more than 0.5 feet measured at right angles to the slope, unless directed or approved by the COR.

3.8 BACKFILL AND FILL PLACEMENT AND COMPACTION

A. General:

1. Obtain approval from COR with regard to suitability of soils and acceptable subgrade prior to subsequent operations.

2 Provide system necessary to successfully complete excavation, SECTION 31 23 00 Page 15 compaction and construction requirements.

3. Place satisfactory soil material in layers to required subgrade elevations.

4. Do not place backfill or fill material within the limits of the new channel on surfaces that are muddy, frozen, or contain frost or ice.

B. Fill/Backfill Placement Near Embankment Dam:

1. Place Common Borrow materials in loose layers not more than 1-foot in loose thickness, unless otherwise specified.

2. Before compaction, moisten or aerate each layer as necessary to provide the optimum moisture content.

3. Compact Common Borrow to at least 92 percent of the material's maximum dry density as determined by ASTM D1557.

4. Compact Granular Borrow to at least 92 percent of the material's maximum dry density as determined by ASTM D1557.

5. Compact Aggregate Base to at least 92 percent of the material's maximum dry density as determined by ASTM D1557.

C. Fill in Spoils Areas: Compact each layer at spoils areas as necessary to facilitate efficient and timely execution of the work.

D. Place backfill and fill materials evenly to required elevations.

3.9 FIELD QUALITY CONTROL TESTINGS

A. Field testing shall be conducted on all soil materials during construction. The Contractor shall subcontract the services of an independent, third-party geotechnical laboratory testing and inspection service to perform testing of any borrow material to be furnished by the Contractor as specified below.

1. Common Borrow:

Test Methodology1 Frequency2

a. Particle-Size Analysis ASTM D422 1 test/2,000cy (combined sieve/hydrometer)

b. Atterberg Limits ASTM D4318 1 test/2,000cy

c. Proctor (Modified) ASTM D1557 1 test/2,000cy

d. Density ASTM D6938 See Note 3.

2. Granular Borrow:

Test Methodology1 Frequency2

a. Particle-Size Analysis ASTM D422 1 test/1,000cy

b. Proctor (Modified) ASTM D1557 1 test/5,000cy

c. Density ASTM D6938 See Note 3.

3. Aggregate Base:

Test Methodology1 Frequency2

a. Particle-Size Analysis ASTM D422 1 test/1,000cy

b. Proctor (Modified) ASTM D1557 1 test/5,000cy

c. Density ASTM D6938 See Note 3.

Notes:

1. Other testing methods may be considered acceptable, based on prior approval of the COR.

2. Testing frequency shall be as listed, at any change in borrow source, or at any discernable change in material delivered to the site (as determined by the COR).

3. Three tests per lift for every 5,000 square foot of material placed.

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B. The Government Representative will establish or designate control points for the work as follows:

1. The horizontal and vertical control monuments designated by the Government Representative will consist of at least four monuments with horizontal and vertical coordinates.

2. Provide without charge, such competent person, tools, stakes, and other materials as Government Representative may require in establishing or designating control points; in establishing construction easement boundaries; or in checking layout, survey, and measurement of work performed by the Contractor.

C. Provide all additional survey, layout, and measurement work required in accordance with Section 01 71 23 Field Engineering.

1. Work performed by a qualified professional engineer or registered land surveyor acceptable to the COR.

2. Locate and protect control points prior to starting site work, and preserve all permanent reference points during construction.

a. Make no changes or relocations without prior written notice to the governing agency.

b. Report to Government Representative when any reference point is lost or destroyed, or requires relocation because of necessary changes in grades or locations.

c. Require surveyor to replace Project control points and all Federal, State, City, County and private land monuments that may be lost or destroyed.

a) Establish replacements based on original survey control.

b) Comply with local and State requirements for monument replacement and restoration.

3. Establish lines and levels, locate and lay out by instrumentation and similar appropriate means.

4. Periodically verify layouts by the same methods.

5. Maintain a complete, accurate log of all control and survey work as it progresses.

6. On request of the Government, submit documentation to verify accuracy of field engineering work.

3.10 EARTHWORK TOLERANCES

A. Channel dimensions are expected to change during construction and will be guided by the Government Representative. Grading above the bankfull elevation of the channel is expected to incur less adjustment.

The Contractor shall proceed with channel and floodplain excavation with the anticipation that the final grades will be at or below the lines and grades shown on the Drawings, and then anticipate adjustments to the same as excavation nears the lines and grades shown on the Drawings to conform to field and pre-dam indicators, including relic pre-dam channel and floodplain materials, stumps, and other indicators.

B. Finished slopes along the daylight edge of the floodplain and within the spoils areas are critical to maintaining the stability of material.

When completed, the average plane of the slopes shall conform to the slopes indicated on the Plans, and no point on the completed slopes shall vary from the designated plane by more than 0.5 feet measured at right angles to the slope, unless directed or approved by the COR.

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3.11 MAINTENANCE

A. Protection of Graded Areas:

1. Protect newly graded areas from traffic and erosion.

2. Keep free of trash and debris.

B. Repair and re-establish grades in settled, eroded, and rutted areas to specified tolerances.

C. Reconditioning Compacted Areas:

1. Where completed compacted areas are disturbed by subsequent construction operations or adverse weather, scarify surface, re-shape, and recompact as specified in subsections 3.7 and 3.8.

3.12 DISPOSAL OF EXCESS AND WASTE MATERIALS

A. Removal from Site:

1. Remove waste materials, including excess and unacceptable excavated material, trash and debris, and properly dispose of it off the property in accordance with Section 02 42 09 Waste Removal and Handling.

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