B08 Amendment 0005 - updated section 31 56 14.pdf

SOLICIATION NO. W91238-B-21-0012

1 of 1 Amendment 05

SACRAMENTO , CALIFORNIA

AMERICAN RIVER COMMON FEATURES

NATOMAS BASIN REACH A

AMENDMENT 05 - SUMMARY:

A) SPECIFICATION 2172

1) Replaced entire Section 31 56 14.

ARCF Natomas Reach A 2172

SECTION TABLE OF CONTENTS

DIVISION 31 - EARTHWORK

SECTION 31 56 14

SOIL-CEMENT-BENTONITE (SCB) CUTOFF WALL - DEEP MIXING METHOD

PART 1 GENERAL

1.1 SUMMARY

1.2 REFERENCES

1.3 GENERAL CONDITIONS

1.3.1 Lines and Grades

1.3.2 Conduct of Work

1.3.3 Access and Ramps

1.3.4 Protection of Existing Facilities

1.3.5 Permits

1.3.6 Construction Method

1.3.7 Sequencing of the Work

1.3.8 Water for Construction

1.4 DEFINITIONS

1.4.1 Cutoff Wall

1.4.2 Bentonite

1.4.3 Portland Cement

1.4.4 Ground Water Level

1.4.5 Working Surface

1.4.6 Key-In Material

1.4.7 Admixtures

1.4.8 Cutoff Wall Specialist

1.4.9 Cutoff Wall Equipment Operator

1.4.10 Quality Control Laboratory

1.4.11 Quality Control Report

1.4.12 Obstructions

1.4.13 Excavation Refusal

1.4.14 Remediation Plan

1.4.15 Elevation Datum

1.4.16 Material Safety Data Sheet (MSDS)

1.5 RELATED SECTIONS

1.6 SUBMITTALS

1.7 QUALITY CONTROL

1.7.1 Rejected Work

1.8 QUALIFICATIONS

1.8.1 Contractor

1.8.2 Soil Mixing Equipment Operator

1.8.3 Soil Mixed Grout Plant Operator

1.8.4 Soil-Mixed Cutoff Wall Specialist

1.8.5 Quality Control Engineer

1.8.6 Quality Control Laboratory

1.9 DELIVERY, STORAGE, AND HANDLING

1.10 GEOTECHNICAL SITE CONDITIONS

1.10.1 Exploration

1.10.2 Ground Water

1.10.3 Knowledge of Subsurface Data

1.11 MAINTENANCE

1.11.1 Extra Materials

SECTION 31 56 14 Page 1

AM05

PART 2 PRODUCTS

2.1 GENERAL

2.2 MATERIAL STORAGE FACILITY

2.3 PORTLAND CEMENT

2.4 BENTONITE

2.5 ADMIXTURES

2.6 WATER

2.6.1 Source

2.6.2 Water Quality

2.7 DMM SOIL-CEMENT-BENTONITE MIXTURE

2.8 MATERIAL STORAGE FACILITY

2.9 ENVIRONMENTAL PROTECTION

2.10 DISPOSAL SITE

2.11 TRENCH PLATES

2.12 EQUIPMENT

2.12.1 DMM Drilling Equipment

2.12.2 DMM Mixing Equipment

2.12.3 Field Laboratory Equipment

2.12.4 Hauling Equipment

2.12.5 Equipment Weight, Speed, and Width

2.13 CONSTRUCTION STAKING

2.13.1 Initial and Final Elevation

2.14 PERMANENT METAL MARKER STAKES

PART 3 EXECUTION

3.1 GENERAL

3.1.1 DMM Cutoff Wall Implementation Plan

3.1.1.1 Soil Mixing Equipment

3.1.1.2 Binder Delivery Methods and Equipment

3.1.1.3 Qualification Submittal

3.1.1.4 Sample Quality Control Records

3.1.1.5 Schedule and Sequence of Operations

3.1.1.6 Sequence Of Operations At Utility Line Crossings

3.1.1.7 Sampling Plan

3.1.1.8 Cutoff Wall Surcharge Loading Plan

3.1.2 Design Requirements

3.1.3 Acceptance Requirements

3.1.4 Demonstration Section

3.1.4.1 Location

3.1.4.2 Mix Design Development

3.1.4.3 Establishment of Mixing Index

3.1.4.4 Core Drilling and Virtual Cores

3.1.4.5 Special Quality Control Testing

3.2 MOBILIZATION

3.3 SITE WORK

3.3.1 Working Surface

3.3.2 Determination of Key-in Layer Depth

3.3.3 Rig Assembly

3.3.4 Grout Plant Assembly

3.3.5 Rig Movement to Work Area

3.4 MATERIAL DELIVERY AND INJECTION

3.4.1 Deliveries

3.4.2 Silo Loading

3.4.3 Batching, Mixing and Agitation

3.4.4 Pumping

3.4.5 Air Injection

SECTION 31 56 14 Page 2

3.4.6 Injection

3.4.6.1 Leads

3.4.6.2 Ports

3.5 EQUIPMENT

3.5.1 Soil Mixing Apparatus

3.5.2 Electronic Sensors

3.5.3 Penetration Depth Marking

3.5.4 Cement/Bentonite Slurry Plant

3.5.5 Replacement Parts

3.6 INSTALLATION

3.6.1 Heading Construction

3.6.1.1 Element Sequencing

3.6.1.2 Element to Element Connections

3.6.1.3 Production Breaks

3.6.1.4 Heading Connections

3.6.2 Element Construction

3.6.2.1 Construction Staking

3.6.2.2 Rig Positioning

3.6.2.3 Material Mixing

3.6.2.4 Mixing Technique

3.6.2.5 Construction Progress

3.6.2.6 Grout Injection Rate

3.6.2.7 Cement Bentonite Slurry Injection Rate Modification

3.6.2.8 Mixing Index Modifications

3.6.3 Depth Modifications

3.7 DEMOBILIZATION

3.7.1 Cleanup

3.7.2 Disposal or Waste Materials

3.7.3 Survey Monuments

3.8 FIELD QUALITY CONTROL

3.8.1 Materials Testing

3.8.1.1 Sample Collection and Testing

3.8.1.2 Grout Testing

3.8.1.3 Wet Bulk Sampling

3.8.1.4 Hydraulic Conductivity Testing

3.8.1.5 Compressive Strength Testing

3.8.1.6 Laboratory Testing

3.8.1.7 Coordination of Testing Laboratories

3.8.2 Rig Instrumentation and Telemetry

3.8.2.1 Installation Records

3.8.2.2 Mixing Technique

3.8.2.3 Wall Continuity

3.8.2.4 Soil Mixing Apparatus Rotation Speed and Penetration and

Withdrawal Rates

3.8.2.5 Cement Bentonite Slurry Injection Rate

3.8.2.6 Modifications to Injection Rate

3.8.2.7 Continuous real time monitoring and recording of the

following soil mixing parameters.

3.8.3 Reporting

3.8.3.1 Materials Testing

3.8.3.2 Daily Reports

3.9 PROTECTION OF CUTOFF WALL

3.10 TEMPORARY CAP

3.11 REMOVAL OF TEMPORARY CAP

3.12 REJECTED DMM CUTOFF WALL SECTIONS

3.13 QUALITY ASSURANCE INSPECTION ANDS TESTING

3.14 CUTOFF WALL CLOSE OUT AND ACCEPTANCE

3.14.1 Construction Records

3.14.2 Construction Documentation

SECTION 31 56 14 Page 3

3.14.3 Construction Quality Control Test Results

3.14.4 Construction Log

3.14.5 As-Built Drawing

3.14.6 Acceptance

3.14.7 Acceptance Criteria

-- End of Section Table of Contents --

SECTION 31 56 14 Page 4

SECTION 31 56 14

SOIL-CEMENT-BENTONITE (SCB) CUTOFF WALL - DEEP MIXING METHOD

PART 1 GENERAL

1.1 SUMMARY

The work covered by this section consists of furnishing all plant, labor, equipment, and materials and of performing all operations in connection with the construction of a seepage cutoff wall, in accordance with these specifications and the applicable Drawings. The cutoff wall construction method addressed in this specification is the Deep Mixing Method (DMM). The intent of the cutoff wall is to provide a continuous, homogenous, low permeability barrier to embankment and foundation seepage within the vertical depth limits and horizontal station limits shown on the Drawings.

The soil-cement-bentonite (SCB) cutoff wall must be constructed from the working surface identified on the Drawings.

The Contractor may choose to construct the cutoff wall sections shown on the Drawings by either the DMM method in accordance with this section, or by Vertical Chain Trenching Method in accordance with Section 31 56 15

SOIL-CEMENT-BENTONITE (SCB) CUTOFF WALL - VERTICAL CHAIN TRENCHING (VCT)

METHOD. If the Contractor chooses to construct adjacent headings using different construction methods, a minimum of 25 feet of overlap at the full cutoff wall depth is required. The Contractor must submit overlap details for review and approval by the Contracting Officer as part of their Cutoff Wall Implementation Plans.

1.2 REFERENCES

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

AMERICAN PETROLEUM INSTITUTE (API)

API RP 13B-1 (2009; R 2016) Recommended Practice for Field Testing Water-Based Drilling Fluids

API Spec 13A (2010; Errata 1 2014; Errata 2-3 2015) Specification for Drilling-Fluid Materials

ASTM INTERNATIONAL (ASTM)

ASTM C150/C150M (2019) Standard Specification for Portland Cement

ASTM D2166 (2016) Standard Test Method for Unconfined Compressive Strength of Cohesive Soil

ASTM D2487 (2017) Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)

SECTION 31 56 14 Page 5

ASTM D2488 (2017; E 2018) Standard Practice for Description and Identification of Soils (Visual-Manual Procedure)

ASTM D4380 (2012) Standard Test Method for Density of Bentonitic Slurries

ASTM D4832 (2016; E 2018) Standard Test Method for Preparation and Testing of Controlled Low Strength Material (CLSM) Test Cylinders

ASTM D5084 (2016) Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter

ASTM D6914 (2016) Standard Practice for Sonic Drilling for Site Characterization and the Installation of Subsurface Monitoring Devices

U.S. ARMY CORPS OF ENGINEERS (USACE)

ER 1110-1-1807 (2014) Engineering and Design -- Drilling in Earth Embankment Dams and Levees

U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)

EPA 600/4-90/027F (1993) Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms

STATE OF CALIFORNIA DEPARTMENT OF TRANSPORTATION (CALTRANS)

Bridge Design Manual (2004) Bridge Design Specifications

CA MUTCD (2012) California Manual on Uniform Traffic Control Devices

California Test Method 342 (2012)Method of Test for Surface Skid Resistance with the California Portable Skid Tester

1.3 GENERAL CONDITIONS

1.3.1 Lines and Grades

The Contracting Officer may at any time prior to or during construction require a change in the cutoff wall depth. The objective of the cutoff wall is to block potential seepage through the levee embankment and/or through the levee foundation materials. The cutoff wall may be optimized by increasing or decreasing the depth of the cutoff wall. The potential variation from the depth indicated in the Drawings is estimated to be plus or minus five feet, but Contractor's equipment must be capable of constructing a cutoff wall 10 feet deeper than the maximum depth indicated on the Drawings.

SECTION 31 56 14 Page 6

1.3.2 Conduct of Work

The Contractor must maintain and protect the cutoff wall in a satisfactory condition at all times until final completion and acceptance of all work under the Contract.

1.3.3 Access and Ramps

See Section 01 50 00 TEMPORARY CONSTRUCTION FACILITIES AND CONTROLS and Section 31 00 00 EARTHWORK for details and requirements for access and ramps.

1.3.4 Protection of Existing Facilities

Construction must be conducted in a manner that avoids damage to all existing facilities that are not designated for removal or reconstruction.

1.3.5 Permits

The Contractor and subcontractors must obtain and pay all necessary fees for all local, state, and federal permits required of the Contractor and subcontractors to accomplish the Work.

1.3.6 Construction Method

The cutoff wall must be constructed using in situ multi-shaft soil mixing methods capable of meeting the requirements of this section and classified as either: Wet Rotary Shaft (WRS), Wet Rotary End (WRE), or Wet Vertical Panel (WVP), as described in the Federal Highway Administration manual Deep Mixing For Embankment and Foundation Support. Methods that do not use mechanical soil cutting or mixing methods are not acceptable. The SCB cutoff wall must be constructed in accordance with these specifications and as shown on the Drawings. The design intent is to produce an incompressible, relatively low-strength, low-permeability, continuous cutoff wall. The cutoff wall must be continuous between the starting and ending points for each alignment, with an appropriate overlap between elements and headings to ensure continuity to full depth. The cutoff wall must consist of either a series of overlapping SCB elements, formed underground through and beneath the levee, or by a full-depth horizontal advancement. Individual elements are joined utilizing overlaps, forming a continuous soil-mixed cutoff wall along the entire alignment.

1.3.7 Sequencing of the Work

The Contractor may use multiple headings to achieve the required schedule completion dates.

1.3.8 Water for Construction

Details regarding water supplies, and the pumping and conveyance of the water, are presented in Section 01 71 10, MOBILIZATION AND DEMOBILIZATION.

This water source will be used for all trial mixes and production.

1.4 DEFINITIONS

1.4.1 Cutoff Wall

The cutoff wall is to be a minimum 27-inch-wide wall installed from the prepared working surface using the DMM method to form a continuous low

SECTION 31 56 14 Page 7 permeability barrier with a specified maximum permeability and within a specified range of unconfined compressive strength.

1.4.2 Bentonite

Bentonite is an ultrafine natural clay whose principal mineral constituent is sodium cation montmorillonite.

1.4.3 Portland Cement

Cement to be used in constructing the DMM cutoff wall must be Portland Cement Type II/V per ASTM C150/C150M. Use of reclaimed cement or cement containing lumps or deleterious matter must not be allowed.

1.4.4 Ground Water Level

The ground water level is the piezometric level of the ground water as shown on the exploration logs in the Geotechnical Data Report. Groundwater levels indicated on the exploration logs were levels found at the time of exploration. The groundwater table can vary significantly depending on time of year, variation from normal precipitation, and the water levels in the Sacramento River and American River.

1.4.5 Working Surface

The working surface is the area along the levee embankment, prepared as shown on the Drawings and described in the Specifications, from which the cutoff wall must be constructed.

1.4.6 Key-In Material

The key-in material is the soil stratum into which the bottom of the cutoff wall is embedded.

1.4.7 Admixtures

Any approved additive used to modify the properties of the soil-cement-bentonite mix.

1.4.8 Cutoff Wall Specialist

The cutoff wall specialist is an individual working for the Contractor who will have responsibility for the construction of the DMM cutoff wall.

1.4.9 Cutoff Wall Equipment Operator

The excavation equipment operator is an individual who will operate the excavation equipment used to construct the DMM cutoff wall.

1.4.10 Quality Control Laboratory

Contractor's quality control laboratory must perform quality control testing on material samples to verify compliance with the Specifications.

1.4.11 Quality Control Report

A report prepared by the Contractor for each shift and for each rig (if multiple headings of the cutoff wall are advanced) that documents the progress on the DMM cutoff wall construction and present the results of the

SECTION 31 56 14 Page 8 quality control inspection and testing.

1.4.12 Obstructions

Culverts, standpipes, and other buried piping that are shown on the Drawings and that are either to be preserved and protected or removed and replaced as part of the work must not be considered obstructions. Existing utilities shown on the drawings must not be considered obstructions.

Man-made objects encountered within the zone excavated to degrade the levee (e.g., utilities and other facilities, etc.) must not be considered obstructions. The Contracting Officer must be the sole judge of whether an obstruction has been encountered. An obstruction will not be considered unless it is the result of natural ground conditions and when using properly operated and maintained equipment. Past performance will be considered when determining whether the equipment is properly operated and maintained, including but not limited to specific rig performance, tooling, and soil conditions, etc.

1.4.13 Excavation Refusal

The rate of cutting head advancement must be less than:

a. 1 foot vertical advancement in 30 minutes for vertically installed elements, or

b. 0.5 foot horizontal advancement in 30 minutes for horizontally installed elements.

1.4.14 Remediation Plan

A plan that describes the steps to be taken by the Contractor to bring any section back into compliance with the specifications.

1.4.15 Elevation Datum

All elevations are referenced to the North American Vertical Datum of 1988 (NAVD-88) in feet.

1.4.16 Material Safety Data Sheet (MSDS)

A detailed informational document prepared by the manufacturer or importer of a hazardous chemical that describes the physical and chemical properties of the product.

1.5 RELATED SECTIONS

Section 01 33 00 SUBMITTAL PROCEDURES

Section 01 45 00 QUALITY CONTROL

Section 01 50 00 TEMPORARY CONSTRUCTION FACILITIES AND CONTROLS

Section 02 32 00 SUBSURFACE DRILLING, SAMPLING, AND TESTING

Section 01 71 10 MOBILIZATION AND DEMOBILIZATION

Section 31 00 00 EARTHWORK

SECTION 31 56 14 Page 9

1.6 SUBMITTALS

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

submittals not having a "G" designation are for information only or as otherwise designated. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following must be submitted in accordance with Section

01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

All Preconstruction Submittals must be submitted no later than 30 calendar days after Notice-to-Proceed.

DMM Cutoff Wall Implementation Plan; G, DO

Including the revised key-in verification explorations plan

Qualification Submittal; G, DO

Sample Quality Control Records; G, DO

Schedule and Sequence of Operations; G, DO

Sequence of Operations At Utility Line Crossings; G, DO

Sampling Plan; G, DO

Cutoff Wall Production Plan; G, DO

Cutoff Wall Surcharge Loading Plan; G, DO

Soil Mixing Operation Plan; G, DO

Description Of The Equipment And Procedures

Remediation Plan; G, DO

Water Quality Test Results; G, DO

Results of the Demonstration Section; G, DO

Drilling Program Plan; G, DO

SD-03 Product Data

Admixtures; G, RO

SD-04 Samples

Wet Bulk Samples

Chain of Custody Form for Quality Assurance Samples

Trial Mix Designs; G, DO

SD-05 Design Data

Cutoff Wall SCB Material Mix Design; G, DO

SECTION 31 56 14 Page 10

Proposed Mix Design And Construction Methods; G, DO

SD-06 Test Reports

Calibration Results

Water Quality Test Report

SCB Mix Design Test Report; G, DO

As-Built Profile of Cutoff Wall and End of Construction Summary Report; G, DO

Construction Quality Control Test Results

Daily Field Quality Control Reports

Demonstration Section Test Report; G, DO

Laboratory Testing Reports; G, DO

Construction Quality Control Test Results; G, DO

Cutoff Wall Key-In Verification Explorations And Monitoring; G, DO

SD-07 Certificates

Cement Certification

Bentonite Certification

Admixture Certification

Calibration of Scales and Flow Meters; G

SD-11 Closeout Submittals

Construction Documentation; G, DO

Construction Records; G, DO

Construction Log; G, DO

As-Built Drawing; G, DO

1.7 QUALITY CONTROL

1.7.1 Rejected Work

Rejected work will be repaired by construction of a new heading between the last two locations of acceptable tests. The new heading will be constructed immediately adjacent to the existing cutoff wall on the waterside.

SECTION 31 56 14 Page 11

1.8 QUALIFICATIONS

1.8.1 Contractor

Qualifying experience in soil-mixed cutoff wall construction projects in within the last 10 years from this solicitation (year issued). Multiple headings on any one contract is considered as one construction project.

The project experience must have been performed by the entity that performs the work as defined below. An individual's experience from former companies does not qualify as soil-mixed cutoff wall construction project experience for the Contractor. The qualifying experience in cutoff wall construction projects must consist of the following: Satisfactorily completed the construction of at least two soil-cement-bentonite (SCB) cutoff walls using the in place soil mixing method. The cutoff wall must have had a minimum depth of 70 feet and a minimum area of 100,000 square feet and a minimum width of 24 inches. The cutoff wall properties must include a maximum permeability of 1 x 10-6 cm/sec. The qualifications and experience of personnel who must be responsible for conducting the operations must include references of the previously completed project owners with owner name; telephone number; address; and project description including depth, length, and construction method of the Contractor's previous successful DMM cutoff wall construction projects. The in situ soil mixing cutoff wall methods must be as classified as either: Wet Rotary Shaft (WRS), Wet Rotary End (WRE), Wet Rotary and Jet End (WJE) or Wet Vertical Panel (WVP), as described in the Federal Highway Administration manual Deep Mixing For Embankment and Foundation Support. Methods that do not use mechanical soil cutting or mixing methods are not acceptable.

1.8.2 Soil Mixing Equipment Operator

The Soil Mixing Equipment Operator(s) must have experience in using similar equipment to be used for this solicitation in a minimum of two successfully completed projects and a minimum of five years of experience similar to the projects described in paragraph Contractor above. The projects listed in the resume must be similar to this solicitation including, but not limited:

comparable scope and complexity.

1.8.3 Soil Mixed Grout Plant Operator

The Grout Plant Operator(s) must have experience in using similar grout plant equipment to be used for this solicitation in a minimum of two successfully completed projects and a minimum of five years of experience similar to the projects described in paragraph Contractor above. The projects listed in the resume must be similar to this solicitation including, but not limited: comparable scope, complexity and physical size completed.

1.8.4 Soil-Mixed Cutoff Wall Specialist

The Soil-Mixed Cutoff Wall Specialist(s) must be experienced in providing supervision of mix design and field control composition and mixing of the soil-cement bentonite using in situ soil mixing equipment. The projects listed in the resume must include a minimum of two successfully completed projects and a minimum of five years of experience on projects similar in scope, project type, physical size and complexity to this solicitation and meeting the project criteria in paragraph Contractor above. The experience must include but not limited to: (1) controlling composition, mixing, placing, sampling, testing and maintaining cement bentonite slurry; (2) supervision of alignment, verticality, and depth of soil mixing equipment;

SECTION 31 56 14 Page 12

(3) controlling blending, mixing, sampling, and testing in-situ material;

and (4) a thorough knowledge of soil mixing and cutoff wall construction equipment and material testing.

1.8.5 Quality Control Engineer

The Quality Control Engineer is a Registered Professional Engineer who is an individual working for the Contractor and is responsible for verifying Contractor's Quality Control Program is being properly implemented and the specified cutoff wall properties are being achieved. The Quality Control Engineer is responsible for cutoff wall construction documentation.

1.8.6 Quality Control Laboratory

The Contractor's Quality Control Laboratory must be an independent commercial laboratory and must comply with the requirements of Section 01 45 00 QUALITY CONTROL and be a USACE accredited laboratory. Submit Quality Control Laboratory Qualifications for approval.

1.9 DELIVERY, STORAGE, AND HANDLING

Protect materials delivered and placed in storage, protected from the weather, soil, dust or other contaminants.

1.10 GEOTECHNICAL SITE CONDITIONS

1.10.1 Exploration

Subsurface cone penetrometer test probes and exploratory borings have been performed by the Government to evaluate subsurface conditions. Approximate locations of the explorations, boring and CPT log descriptions, levee embankment and subsurface materials encountered during explorations are included in the Natomas Reach A Geotechnical Data Report for the convenience of the Contractor. The Natomas Reach A Geotechnical Data Report is included in the Supplemental Information Package of the solicitation. The Government assumes no responsibility for interpretations made by the Contractor from the explorations. Local variations in the subsurface materials are to be expected and, if encountered, will not be considered as being materially different within the purview of this contract. Construction verification exploration of cutoff wall depth requirements is addressed in paragraph DETERMINATION OF KEY-IN LAYER DEPTH.

1.10.2 Ground Water

A description of the ground water condition is presented in the Geotechnical Data Report.

1.10.3 Knowledge of Subsurface Data

It is the Contractor's responsibility to become acquainted and satisfied as to the character, quality, and quantity of surface and subsurface materials by inspecting the site, performing additional borings as necessary for soil classification and mix design formulation and by evaluating information derived from the exploration work performed for this project and included in these plans and specifications. Any failure by the Contractor to become acquainted with all the available information and any other site specific conditions such as utilities will not relieve the Contractor from responsibility for properly estimating the difficulty or cost of successfully performing the work.

SECTION 31 56 14 Page 13

1.11 MAINTENANCE

1.11.1 Extra Materials

Maintain at the job site a sufficient quantity of raw materials and other supplies such that the work can proceed uninterrupted by material shortages. Modify the mix proportions and methods as needed to meet the required wall strength, permeability, continuity, and homogeneity and difficult subsurface conditions. Perform additional tests necessary to verify compliance with the Acceptance criteria.

PART 2 PRODUCTS

2.1 GENERAL

The Contractor must maintain at the job site a sufficient quantity of raw materials and other supplies such that the work can proceed uninterrupted by material shortages. The Contractor must, if necessary, modify the DMM SCB cutoff wall design mixes to meet the requirements for permeability, strength, continuity, and homogeneity specified in this Specification section. The Contractor must undertake any additional tests necessary to assist in material selection, to verify compliance with the Specifications, and to demonstrate the characteristics of the cutoff wall.

2.2 MATERIAL STORAGE FACILITY

The Contractor must provide all necessary materials, equipment and personnel to store the bentonite, cement and other additives under conditions to prevent moisture or other contaminants from interacting or mixing with the materials prior to use in the plant.

2.3 PORTLAND CEMENT

Cement must be Portland Cement Type II or Type V (per ASTM C150/C150M).

Provide a record copy cement supplier recent written certificate (less than 1 year old) specifying cement quality. The Cement Certification submittal must correspond to the current source of cement. Submit statement(s) signed by an authorized official to certify on behalf of the manufacturer of the materials attesting that the products meet specified requirements.

The statement must be dated after the award of the Contract, must state the Contractor's name, address, must name the project and location, and must list the specific requirements which are being certified.

2.4 BENTONITE

Furnish a recent, written Bentonite Certification (less than 1 year old) and a copy of the test reports from the bentonite supplier for each lot of bentonite shipped to the site stating that the bentonite complies with all applicable standards. The bentonite must be sodium cation base montmorillonite powder that conforms to API Spec 13A, Section 9 or 10.

Bentonite must be new, pulverized, high-swelling natural sodium cation montmorillonite (Premium Grade Wyoming-type bentonite). No bentonite from the bentonite manufacturer must be used prior to acceptance by the Contracting Officer. All bentonite must be subject to inspection, sampling, and verification of quality by Contractor QC testing and Government QA testing. Bentonite not meeting specifications must be promptly removed from the site and replaced with bentonite conforming to specification requirements at the Contractors expense. Protect bentonite

SECTION 31 56 14 Page 14 from moisture during transit and storage. Submit statement(s) signed by an authorized official to certify on behalf of the manufacturer of the materials attesting that the products meet specified requirements. The statement must be dated after the award of the Contract, must state the Contractor's name, address, must name the project and location, and must list the specific requirements which are being certified.

2.5 ADMIXTURES

Submit proposed use of admixtures, for to approval. Provide written documentation supporting the proposed use of all admixtures. Documentation must address the effects of the admixture on the cutoff wall SCB material, long-term stability and the admixture and the SCB material, and any potential effects on the natural environment. Peptzing or bulking agents must not be mixed with the cement or bentonite slurry. Admixtures must be proven with the trial design mixes. Use only admixtures approved by the Government. Retarders, fly ash, or other solids containing heavy metals are prohibited. Submit a recent (less than 1 year old) Admixture Certification for each lot of admixtures.

2.6 WATER

2.6.1 Source

Refer to Section 01 50 00, TEMPORARY CONSTRUCTION FACILITIES AND CONTROLS for information on potential water supplies and the requirements that apply to providing the water supply for construction of the Project. Provide the water sources used for production and associated pH, hardness, total dissolved solids analysis (water sources used for production must be same as trial mix). City hydrants if used by Contractor must be identified in work plan: (1) note the locations of hydrants for use, and (2) procure appropriate permits. The Contractor must abide by any and all regulations and other requirements governing such use. The Contractor must include the cost of all related fees in the bid items pertinent to the Work.

2.6.2 Water Quality

The water must comply with the standards specified below. The Contractor must furnish Water Quality Test Results for water used for mixing with the slurry to assure conformance with these standards.

Property Property Requirement Test Method pH Vale 7.0 +/- 1.0 API RP 13B-1

Total Dissolved Solids <500 ppm EPA 600/4-90/027F

Oil, organics, acids, or other deleterious

<50 ppm each API RP 13B-1

Hardness <50 ppm API RP 13B-1

Water quality variances may be accepted for use based upon performance in the SCB mix as long as the required permeability and strength standards specified herein for the in place SCB wall are achieved throughout the project. Furnish water quality test results for water used for mixing the bentonite slurry and cement slurry to assure conformance with the above limits. Water used for production must come from the same source as water

SECTION 31 56 14 Page 15 used for the mix design. Abide by any and all Federal, State of California, and local regulations and other requirements governing such use. Include the cost of all related fees in the bid items pertinent to the work. Water must not be taken from the river for construction activities, except when required for testing and with the Contracting Officer's approval. Water taken from the river for testing purposes must only be filled by hand, and mechanical pumps are prohibited. Submit a Water Quality Test Report presenting the results of the testing.

2.7 DMM SOIL-CEMENT-BENTONITE MIXTURE

The procedures by which the Contractor will inject, calculate, and monitor quantities of bentonite, cement, and water must be defined by the Results of the Demonstration Section of the successfully constructed cutoff wall.

The SCB mixture must consist of in situ soil mixed with water (both in situ and added), cement, and bentonite to form a low permeability wall. The cement and bentonite must consist of either a slurry mixture or dry application with water injection as needed for the DMM method. The cement and bentonite must meet the requirements specified. The initial mixture must contain a minimum of four percent bentonite and five percent cement by dry weight of soil. The final mix proportions must be determined by the testing result of the required demonstration section. Based on the results of the specified demonstration section, the bentonite and/or cement quantities must be adjusted by the contractor as necessary, and as approved by the Contracting Officer to achieve the properties specified below at no additional cost to the Government. The SCB mixture in the must have the following properties must meet the requirements in Paragraph ACCEPTANCE

REQUIREMENTS.

The initial design mix may be adjusted by the Contractor if necessary and if approved by the Contracting Officer based on the results of the Demonstration Section and to adapt to changes in field conditions at no additional cost to the Government.

Submit a record of DMM injection materials (cement, bentonite, and water quantities), introduced into the cutoff well including any additives utilized, and adjustments for each production shift including the date mixed and stations completed.

2.8 MATERIAL STORAGE FACILITY

The Contractor must provide all necessary materials, equipment and personnel to store the bentonite, cement, and other additives under conditions to prevent moisture or other contaminants from mixing with the materials prior to use.

2.9 ENVIRONMENTAL PROTECTION

The raw materials and other supplies used in the construction of the DMM SCB cutoff wall and any spoil disposed of must be non-hazardous and must comply with Section 01 57 19 TEMPORARY ENVIRONMENTAL CONTROLS to prevent, and provide for abatement and control of, any environmental pollution arising as a part of the work.

2.10 DISPOSAL SITE

Cutoff wall trench excavated material that is not suitable for use per Section 31 00 00 EARTHWORK must be disposed of off-site at the Contractor's

SECTION 31 56 14 Page 16 expense.

2.11 TRENCH PLATES

The minimum plate thickness must be 1-1/4 inches for the specified trench width. Steel plates also known as steel plate bridging must consist of steel designed for HS20-44 truck loading per Caltrans Bridge Design Manual.

The Contractor must maintain on the steel plates a non-skid surface having a minimum coefficient of friction of 0.35 as determined by California Test Method 342. The trench plates must extend a sufficient distance beyond the edge of the trench walls so that load transfer from the plates does not impact trench stability during curing and strength development of the wall.

2.12 EQUIPMENT

Furnish all necessary plant and equipment for use on this Project. The Contractor must obtain and maintain at the jobsite a supply of spare critical replacement parts or backup equipment sufficient to allow the cutoff wall construction to proceed with minimum loss of time due to mechanical breakdown or equipment failure. Calibration of Scales and Flow Meters must be provided by the Contractor.

2.12.1 DMM Drilling Equipment

The equipment must be capable of excavating the required minimum width of trench. The equipment must be able to excavate 10 feet deeper than the maximum depth shown on the Drawings in the areas the equipment is proposed for use. The Contractor must provide written description on the method for verifying vertical tolerance and must be accepted by the Contracting Officer as part of the Cutoff Wall Implementation Plan submittal package.

If there is instability of the cutoff wall due to equipment excavation, the Contractor must repair the wall at no expense to the Government.

2.12.2 DMM Mixing Equipment

The DMM equipment used for batching and mixing the cement, bentonite, and injected water must be capable of mixing the materials into a homogeneous mixture conforming to the contract specification requirements. Mixing equipment must be capable of continually mixing the in situ trench material to provide and maintain a uniform blended cutoff wall.

The DMM equipment must have a controlled weighing or metering system for assuring that the dry and/or wet constituents of the mixture are properly proportioned. If a dry mixture is used, the proportions and rates of injection of cement, bentonite, and any added water must be continuously monitored and recorded. If wet cement bentonite slurries are pumped, appropriate mixing and storage tanks must be provided and the slurry density, flow rates, and total volume of slurry pumped must be obtained using a data acquisition system.

The rate of material use must be made available for Government inspection so that the proportions of the various mixes can be checked. Data acquisition display must be easily accessible to QA inspectors and must not interfere with Contractor's activities. At the end of each shift, the Contractor must submit a hardcopy output of all the data collected along with a digital record of the materials used. Digital record must be compatible with Windows XP for import into Microsoft Excel or another

SECTION 31 56 14 Page 17 approved spreadsheet by the Contracting Officer.

2.12.3 Field Laboratory Equipment

The Contractor's field laboratory equipment for Contractor's quality control testing must be made available for Government testing at any time and must contain, at a minimum, the following equipment:

1. Two Marsh funnel sets (API RP 13B-1)

2. One standard filter press

3. Two mud balances (direct reading of density)

4. One slurry sampler

5. Two No. 200 sieves

6. One set of standard sieves and sieve shaker

7. One oven for moisture content

8. One scale

9. One pH meter

10. Two slump cones

11. Adequate number of 3-inch by 6-inch cylindrical sample molds

2.12.4 Hauling Equipment

Earthwork related hauling equipment must consist of pneumatic-tired vehicles with bodies suitable for the material being hauled and meeting the requirements of paragraph EQUIPMENT WEIGHT, SPEED, AND WIDTH.

2.12.5 Equipment Weight, Speed, and Width

Weight of equipment to be used on the levee crown must be limited to a maximum gross loaded axle weight of 34,000 pounds for trucks. For tracked vehicles, the maximum ground pressure allowed is 2,500 pounds per square foot. The maximum weight of the excavator must not exceed 300,000 pounds without prior approval of the Contracting Officer and after evaluation of the Contractor of the effect on levee stability by use of stability analyses. The maximum operating speed of all equipment used on the levee crown or levee toe roads must be 15 mph.

2.13 CONSTRUCTION STAKING

The Contractor must provide, install and maintain all layout and necessary construction staking to locate the cutoff wall centerline within the alignment of the cutoff wall and the cutoff wall length as shown on the Drawings. Surveyor's caps, appropriately identified to include survey control number and name of survey company and mounted on a 2-inch diameter, 2-foot-long steel pipe, driven into the ground, must be provided at each end of the cutoff wall. Wooden stakes must be placed along the cutoff wall centerline at 100-foot maximum intervals between the ends. Coordinates and elevations must have units consistent with the Drawings. A tabulated list containing survey control numbers, grid coordinates, project station number, and elevations must be submitted to the Contracting Officer within five working days of completing each heading and a summary list at the completion of all survey controls. The beginning and ending of the cutoff wall and utility crossings must be identified on this list. Survey construction control staking must be performed by a California licensed surveyor and all survey data must be stamped by the licensed surveyor.

2.13.1 Initial and Final Elevation

The survey caps at ends of the cutoff wall must be surveyed to establish

SECTION 31 56 14 Page 18 initial elevation and final elevation to an accuracy of plus or minus 0.1-foot and these stakes must be maintained and protected from damage or movement throughout the work. The Contractor must submit a report to the Contracting Officer for the cutoff wall installation showing any settlements that occurred and also indicating the final restored levee crown elevation in comparison to the pre-construction elevation. The cutoff wall stations must have the theoretical maximum elevations of the bottom of the cutoff wall established, and furnished as part of the submittal. A system for locating stations along the cutoff wall alignment and relating them to the Drawings must be established by the Contractor and submitted to the Contracting Officer for approval.

2.14 PERMANENT METAL MARKER STAKES

Upon completion of the cutoff wall installation, permanent metal markers stakes meeting the requirement of Type L-1 Object Markers of CA MUTCD must be placed. In-lieu of the yellow reflective sheeting referenced in the Type L-1 Object Markers, the station location and levee mile of the cutoff wall ends must be placed on the marker. The markers must be surveyed in at the corresponding projected station location and installable at the landside toe of the levee at the cutoff wall ends.

PART 3 EXECUTION

This section describes the portion of the work to be performed. Furnish all plant, equipment, labor, and materials required to construct a cutoff wall as shown on the drawings and specifications.

3.1 GENERAL

The cutoff wall must be constructed to the elevations, lines, grades, and cross sections shown in the Drawings and in accordance with these specifications, unless otherwise directed. The Contracting Officer may modify the dimensions and quantities of the work as determined necessary.

3.1.1 DMM Cutoff Wall Implementation Plan

The Contractor must submit a DMM Cutoff Wall Implementation Plan including the required key-in exploration plan, construction schedule, sequence of operations, equipment date, and quality control plan details.

Describe the general work sequence and layout of operations, work hours, and number of headings. Include scale drawings which depict DMM preparation and storage areas in the layout of operations. The plan must describe Contractor equipment, method of trench excavation, disposal of excavated material, bentonite preparation and placement, and site clean-up.

Detail procedures for locating the cutoff wall in the field and confirming that the cutoff wall is plumb. Provide data and operations manuals on the trench depth measuring equipment. Include a detail plan and procedure for monitoring and addressing slurry loss through the levee.

Describe the quality control program including quality control equipment, testing and sampling equipment, and all required test procedures, sample test forms for reporting test results, onsite and/or offsite laboratory proposed for use, sample storage on site and method of transporting samples to laboratory. Include a reporting schedule for completed DMM mix density tests, gradation tests, permeability tests, unconfined compressive strength tests, and offsite independent laboratory. The implementation plan will be revised as necessary following the interpretation of results and successful

SECTION 31 56 14 Page 19 completion of the Demonstration Section.

The implementation plan must include the data on the equipment used in the construction of the cutoff wall; equipment used to obtain QA samples of the completed cutoff wall; and equipment used in the Contractors quality control testing and measuring. This data must include mixing equipment, storage and delivery equipment and metering and weighing systems.

Procedures must include methods for locating the cutoff wall in the field and confirming that the cutoff wall is in vertical tolerances. Data on equipment used for measuring the trench depth must be submitted as well as any applicable operations manual.

3.1.1.1 Soil Mixing Equipment

Data on equipment to be used in all sequences of the cutoff wall construction, including mixing, placement, and equipment to be used in the CQC testing. Include the location of the laboratory trailer/structure.

Submit a detailed description of the equipment and procedures to be used during the project including, but not limited to, construction of the cutoff wall and monitoring the quality control parameters outlined herein, and collecting samples for laboratory testing. Procedures must include methods for locating the wall in the field and confirming that the wall is plumb. Also submit the proposed mix design and construction methods needed to comply with the drawings and specifications. The calibration of the cement bentonite slurry mixing plants and blending of the cement bentonite slurry must be documented. Include data on equipment such as mixers capable of producing both a stable colloidal suspension of cement bentonite slurry; storage facilities including tanks and methods of agitation;

delivery methods and equipment; spillage, and containment facilities to control spillage.

3.1.1.2 Binder Delivery Methods and Equipment

Data on equipment such as mixers capable of producing a stable colloidal suspension of cement, bentonite slurry, or other mix combinations; storage facilities including tanks and methods of agitation; and delivery methods and equipment.

3.1.1.3 Qualification Submittal

Submit documentation supporting the requirements of QUALIFICATIONS.

Resumes must include dates, durations, projects and owners.

3.1.1.4 Sample Quality Control Records

Submit sample Quality Control Records. Include sample daily field reports, and laboratory test results.

3.1.1.5 Schedule and Sequence of Operations

Submit a proposed sequence of operations for the cutoff wall, showing schedule of demonstration section, headings, elements, etc.

3.1.1.6 Sequence Of Operations At Utility Line Crossings

Submit a proposed plan to accommodate all utility crossings. This plan must be coordinated with the utility owner before submittal.

SECTION 31 56 14 Page 20

3.1.1.7 Sampling Plan

Submit a description of the apparatus and procedures which will be used to obtain wet samples at the various depths required. A detailed drawing and written explanation of how the sampling mechanism operates must be provided. The plan must be reviewed and approved by the Contracting Officer.

3.1.1.8 Cutoff Wall Surcharge Loading Plan

Submit a Cutoff Wall Surcharge Loading Plan describing all surcharge loads applied to the cutoff wall during cutoff wall construction. This plan must show the distance between all surcharge loads applied and the top of the cutoff wall during cutoff wall construction. This plan must include the surcharge loads from materials and equipment and must compare the loads against the strength of completed work. This plan must also include surcharge loads from materials and equipment at approved equipment crossing points. This plan must also include requirements for minimum cover and/or additional protective measures for the completed cutoff wall.

3.1.2 Design Requirements

The DMM cutoff wall must be constructed in accordance with these specifications and as shown on the Drawings. The design intent is to produce an incompressible, relatively low-strength, low-permeability, continuous cutoff wall. The cutoff wall should be continuous between the starting and ending points for each alignment, with an appropriate overlap between elements and headings to ensure continuity to full depth. The cutoff wall must consist of either a series of overlapping SCB elements, formed underground through and beneath the levee, or by a full-depth horizontal advancement. Individual elements are joined utilizing overlaps, forming a continuous soil-mixed cutoff wall along the entire alignment.

3.1.3 Acceptance Requirements

Final acceptance of the cutoff wall will be based on the Quality Control (CQC) Records as identified in the Rig-Shift Reports, Construction Quality Control test results, and Government's quality assurance test results.

Both Contractor and the Government testing must demonstrate that the Contract requirements are met prior to acceptance of the work. If during the course of construction, the Contractor QC testing indicates noncompliance with these specifications, immediately notify the Contracting Officer in writing. Notification must include the remedial action to be taken to bring the work/products back into compliance. The following is the acceptance criteria for the wall. Items a through g below refer to both the demonstration section and production work. In the event a dispute about the quality of the cutoff wall in the production work, the items in the Demonstration Section Only will be used to evaluate the quality in the disputed location. Refer to the entire specification and drawings for all the Contract requirements.

a. Wall bottom elevation: As shown on the drawings or as modified by the verification borings, or as directed by the Contracting Officer.

b. Width of wall: 27 inch as measured in the horizontal plane perpendicular to the wall alignment.

c. Wall continuity: All elements connected by an overlap meeting the requirements of the respective overlap type.

SECTION 31 56 14 Page 21

d. Wet bulk sample unconfined compressive strength: At 28 days, minimum 10-test running average of 200 psi, with no single test below 120 psi.

e. Wet bulk sample permeability: Maximum 5x10-7 cm/sec.

f. Mixing index with allowed deviation established during demonstration section (Mixing Index is defined in Mixing Index Development).

g. Homogeneity which is defined as no unmixed soil inclusions greater than three inches. Defects are defined as incomplete soil-mixed zones greater than 3-inches maximum diameter, as indicated by the cutoff wall cores and the downhole probe sensors. These include voids, seams, cracks or other fissures that indicate the presence of unmixed zones.

Cracks that are caused by mechanical (i.e. from drill tooling) or hydraulic (i.e. hydro-fracturing) action during drilling of the borehole are not considered defects.

3.1.4 Demonstration Section

A demonstration section is required before production work is permitted to proceed.

3.1.4.1 Location

The demonstration section must consist of 100 linear feet of cutoff wall.

The demonstration section must be located within the Cutoff Wall Alignment. The depth of cutoff wall in the demonstration section must be at least the same depth for the production cutoff wall. Establish the cement and bentonite dosage and mixing index in the demonstration section.

3.1.4.2 Mix Design Development

Begin the trial mix designs within seven calendar days from the Notice to Proceed (NTP). Develop a laboratory testing program to demonstrate the adequacy of the proposed SCB mix design. The test materials must be taken from materials collected from at least three separate locations within the limits of the cut off wall; however, fabricate a sufficient number of samples and trial mix designs to support the basis for the proposed mix design. The trial mix designs must cover a range of percentages of bentonite, cement, and admixtures to correlate anticipated ranges of soil gradations. The mixes must contain a minimum of four percent bentonite and five percent cement by dry weight of soil. The minimum number of mix designs must be four.