Amendment 0004 - Specification Revision.pdf

American River Common Features 2016 2342 Sacramento River East Levee, Contract 2

SECTION TABLE OF CONTENTS

DIVISION 31 - EARTHWORK

SECTION 31 56 13.32

SLAG CEMENT-CEMENT-BENTONITE (SCCB) CUTOFF WALL - OPEN TRENCH

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 Slurry Trench

1.4.3 Bentonite

1.4.4 Portland Cement

1.4.5 Slag Cement

1.4.6 Slurry Method of Excavation

1.4.7 Slag Cement-Portland Cement-Bentonite Slurry (SCCB Slurry)

1.4.8 Ground Water Level

1.4.9 Working Surface

1.4.10 Key-In Material

1.4.11 Initial Set

1.4.12 Admixtures

1.4.13 SCCB Cutoff Wall Specialist

1.4.14 Slurry Cutoff Wall Excavation Equipment Operator

1.4.15 Trench Logger

1.4.16 Trench Quality Control Technician (TQCT)

1.4.17 Quality Control Engineer

1.4.18 Quality Control Laboratory

1.4.19 Quality Control Report

1.4.20 Excavation Refusal

1.4.21 Obstructions

1.4.22 Remediation Plan

1.4.23 Elevation Datum

1.4.24 Material Safety Data Sheet (MSDS)

1.4.25 Panel and/or Segment

1.5 SUBMITTALS

1.6 QUALIFICATIONS

1.6.1 Contractor Qualifications

1.6.2 Foreman

1.6.3 Qualifications of Slurry Cutoff Wall Specialist and Slurry

Cutoff Wall Excavation Equipment Operators

1.6.3.1 Slurry Cutoff Wall Specialist

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AMD-04

1.6.3.2 Slurry Cutoff Wall Excavation Equipment Operator

1.6.4 Trench Quality Control Technician (TQCT)

1.6.5 Trench logger

1.6.6 Quality Control Engineer

1.6.7 Quality Control Laboratory

1.7 DELIVERY, STORAGE, AND HANDLING

1.8 GEOTECHNICAL SITE CONDITIONS

1.8.1 Exploration

1.8.2 Subsurface Conditions

1.8.3 Groundwater

1.8.4 Knowledge of Subsurface Data

PART 2 PRODUCTS

2.1 GENERAL

2.2 PORTLAND AND SLAG CEMENT

2.3 BENTONITE

2.4 ADMIXTURES

2.5 WATER

2.5.1 Water Standards

2.5.2 Hydrants

2.6 SCCB MIX DESIGN

2.7 PROPERTIES OF BENTONITE SLURRY IN MIXING AREA

2.8 PROPERTIES OF SCCB SLURRY

2.9 PROPERTIES OF SCCB SLURRY CUTOFF WALL

2.10 MATERIAL STORAGE FACILITY

2.11 ENVIRONMENTAL PROTECTION

2.12 DISPOSAL SITE

2.13 TRENCH PLATES

2.14 EQUIPMENT

2.14.1 Trench Excavation Equipment

2.14.2 SCCB Slurry Mixing Equipment

2.14.3 Field Laboratory Equipment

2.14.4 Slurry Transporting Equipment

2.14.5 Hauling Equipment

2.14.6 Equipment Weight, Speed, and Width

2.15 CONSTRUCTION STAKING

2.15.1 Initial and Final Elevation

2.16 PERMANENT METAL MARKER STAKES

PART 3 EXECUTION

3.1 GENERAL

3.1.1 SCCB Slurry Cutoff Wall Implementation Plan

3.2 SITE WORK AND WALL DEPTH

3.3 WORKING SURFACE

3.3.1 Construction Staking

3.3.2 Construction of Working Surface

3.4 SLURRY TRENCH EXCAVATION

3.4.1 General

3.4.1.1 Existing Cutoff Wall Overlap

3.4.2 Starter Trench

3.4.3 Vertical Tolerance

3.4.4 Bottom Depth

3.4.5 Trench Stability and Slurry Loss

3.4.6 Monitoring for Levee Cracking and Slurry Leakage

3.4.7 Continuity of Cutoff Wall

3.4.8 Premature Hardening of SCCB Slurry

3.4.9 Trench Excavation

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3.4.10 Trench Bottom Cleaning

3.4.11 Top of Cutoff Wall

3.5 SCCB SLURRY CUTOFF WALL CONSTRUCTION

3.5.1 Slurry Mixing and Storage

3.5.2 Mixing Areas

3.5.3 Slurry Placement

3.5.4 Temporary Soil Cap

3.5.5 Removal of Temporary Soil Cap

3.5.6 High Water Event

3.5.7 Cutoff Wall Protection

3.5.8 Cleanup

3.5.9 Slurry Temperature Control

3.6 AS-BUILT PROFILE

3.7 MIXING WATER AND WASH WATER

3.7.1 Mixing Water

3.7.2 Wash Water

3.8 QUALITY CONTROL

3.8.1 General

3.8.2 Access to Work Site

3.8.3 Cutoff Wall Mix Quantities

3.8.4 Water Source

3.8.5 Mixing Area Sampling

3.8.5.1 Slurry Sampling in Mixing Area

3.8.5.2 Slurry Sampling in Trench

3.8.6 Logging of Trench Excavation

3.8.7 Trench Sounding

3.8.8 Trench Sampling for Compressive Strength and Hydraulic

Conductivity

3.8.9 Protocol for Custody of Samples

3.8.10 Testing

3.8.10.1 Field Testing Mix Areas

3.8.10.2 Laboratory Testing

3.8.10.3 Hydraulic Conductivity Testing

3.8.10.4 Compressive Strength Testing

3.8.10.5 Coordination of Testing Laboratories

3.8.11 Quality Control Reports

3.8.11.1 Daily Quality Control Report

3.8.11.2 Weekly Quality Control Report

3.8.12 Quality Control Records

3.8.13 Construction Log

3.8.14 Rejected Cutoff Wall Sections

3.9 QUALITY ASSURANCE INSPECTION AND TESTING

3.10 CUTOFF WALL CLOSEOUT AND ACCEPTANCE

3.10.1 Construction Records

3.10.2 Construction Documentation

3.10.3 Construction Quality Control Test Results

3.10.4 As-built Drawing

3.10.5 Acceptance

3.10.6 Acceptance Criteria Synopsis

-- End of Section Table of Contents --

SECTION 31 56 13.32 Page 3

SECTION 31 56 13.32

SLAG CEMENT-CEMENT-BENTONITE (SCCB) CUTOFF WALL - OPEN TRENCH

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 applicable Plans. The slag cement-cement-bentonite (SCCB) cutoff wall construction method addressed by this Specification is the open trench slurry cutoff wall method using a self-hardening slurry consisting of a mixture of slag cement, portland cement, bentonite, and water. The intent of the cutoff wall is to provide permanent, continuous, homogeneous, low permeability barrier to embankment and foundation seepage within the vertical depth limits and horizontal station limits shown on the Plans. The cutoff wall must consist of a series of overlapping wall elements formed by the slurry trench excavation method. The cutoff wall must be constructed from a working surface as shown on the Plans through the levee embankment and foundation using slag-cement-cement-bentonite (SCCB) slurry as the initial stabilization method. The SCCB then sets to form a low permeable barrier.

All work under this section must comply with the requirements of EM 385-1-1 .

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 (2018) Standard Specification for Portland Cement

ASTM C191 (2013) Standard Test Method for Time of Setting Hydraulic Cement by Vicat Needle

ASTM C940 (2016) Standard Test Method for Expansion and Bleeding of Freshly Mixed Grouts for Preplaced-Aggregate Concrete in the Laboratory

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ASTM C989/C989M (2018a) Standard Specification for Slag Cement for Use in Concrete and Mortars

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

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

ASTM D3740 (2019) Minimum Requirements for Agencies Engaged in the Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction

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

ASTM D6910 (2009) Standard Test Method for Marsh Funnel Viscosity of Clay Construction Slurries

U.S. ARMY CORPS OF ENGINEERS (USACE)

EM 385-1-1 (2014) Safety and Health Requirements Manual

STATE OF CALIFORNIA DEPARTMENT OF TRANSPORTATION (CALTRANS)

Bridge Design Manual (2004) Bridge Design Specifications

CA MUTCD (2014) California Manual on Uniform Traffic Control Devices

1.3 GENERAL CONDITIONS

1.3.1 Lines and Grades

The Government 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 Plans is estimated to be plus or minus 5 feet, but Contractor's excavating equipment must be capable of excavation up to 10 feet deeper than the maximum depth indicated on the Plans, except that where wall depths are shown to be greater than 80 feet on the Plans this requirement will not apply.

SECTION 31 56 13.32 Page 5

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.

Additional requirements for the protection of existing facilities are provided in the Contract Documents. Construction must not interfere with the use of public parks, boat ramps, and bike paths except where noted in these Specifications or the Plans.

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 SCCB slurry cutoff wall must be constructed using a mixture of water, slag cement, portland cement, and bentonite mixed in proper proportions to achieve stable trench excavation and self-hardening setting in place to achieve the acceptance criteria of these Specifications.

1.3.7 Sequencing of the Work

The Contractor may use multiple headings to achieve the required schedule completion dates. The Contractor must consult the Contract Documents for any information regarding using multiple work shifts per day 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 50 00 TEMPORARY CONSTRUCTION FACILITIES AND CONTROLS. This water source must be used for all trial mixes and production.

1.4 DEFINITIONS

1.4.1 Cutoff Wall

The cutoff wall is a minimum 30-inch-wide trench constructed from the working surface using self-hardening SCCB slurry as both the stabilizing agent and permanent wall material to form a low permeability cutoff wall with a specified maximum permeability and range of unconfined compressive strength. As used in these Specifications the terms "permeability" and "hydraulic conductivity" are synonymous.

SECTION 31 56 13.32 Page 6

1.4.2 Slurry Trench

The slurry trench is a minimum 30-inch wide trench excavated through the existing ground or prepared working surface using the slurry method of excavation.

1.4.3 Bentonite

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

1.4.4 Portland Cement

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

1.4.5 Slag Cement

Slag cement to be used in the SCCB cutoff wall slurry must be ground granulated blast-furnace slag cement grade 120.

1.4.6 Slurry Method of Excavation

The slurry method of excavation consists of excavating a vertical walled trench while keeping the trench filled with SCCB slurry. The purpose of the slurry is to support the walls of the trench while excavating to the design depth and, when hardened, to provide the required cutoff wall properties.

1.4.7 Slag Cement-Portland Cement-Bentonite Slurry (SCCB Slurry)

SCCB slurry is a colloidal mixture of ordinary Type I-II or Type II portland cement, ground granulated blast-furnace slag cement grade 120 or higher, bentonite (hydrated for a minimum of 8 hours prior to mixing with cementitious materials), water, and additives mixed to form a stable, semi-rigid, low permeability barrier when the slurry mixture sets.

1.4.8 Ground Water Level

The ground water level is the piezometric level of the ground water as shown on the exploration logs. 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.

1.4.9 Working Surface

The working surface is the top of the degraded levee crown, prepared as shown on the Plans and described in the Specifications, from which the cutoff wall must be constructed.

1.4.10 Key-In Material

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

SECTION 31 56 13.32 Page 7

1.4.11 Initial Set

The time of setting measured using a vicat needle in accordance with

ASTM C191.

1.4.12 Admixtures

Any approved additive used to modify the properties of the SCCB slurry.

The Contractor must submit a copy of the admixtures test results from the admixture manufacturer for each lot of fluidifiers, retarders, softening agents, or as approved, shipped to the site and a certificate of compliance stating that the admixture complies with all applicable standards. The Government may require justification demonstrating that the use of the proprietary or non-proprietary admixture will not be detrimental to the long term performance of the SCCB cutoff wall.

1.4.13 SCCB Cutoff Wall Specialist

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

1.4.14 Slurry Cutoff Wall Excavation Equipment Operator

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

1.4.15 Trench Logger

The trench logger is an individual working for the Contractor who will have responsibility for logging the description and classification of the material excavated from the slurry trench.

1.4.16 Trench Quality Control Technician (TQCT)

The TQCT working under the direction of the Contractor's slurry cutoff wall specialist will take required measurements of trench geometry, perform trench slurry and backfill sampling, and perform trench soundings.

1.4.17 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.

1.4.18 Quality Control Laboratory

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

1.4.19 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 SCCB slurry cutoff wall construction and presents the results of the quality control parameter monitoring.

SECTION 31 56 13.32 Page 8

1.4.20 Excavation Refusal

The Contracting Officer will determine when excavation refusal is reached. Excavation refusal will be defined as the inability of the Contractor's approved production excavator to excavate more than 1 foot of depth over a bottom trench length of 20 feet in a period of 30 minutes with excavator equipment in proper and effective operating condition.

1.4.21 Obstructions

The Contracting Officer will be the sole judge of whether an obstruction has been encountered. Culverts, standpipes, and other buried features that are shown on the Plans 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 Plans or marked by Underground Service Alert (USA) must not be considered obstructions.

Naturally-occurring materials such as cobbles must not be considered obstructions.

1.4.22 Remediation Plan

A plan that describes the steps to be taken by the Contractor to correct deficiencies with the specifications in any section of cutoff wall.

1.4.23 Elevation Datum

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

1.4.24 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.

1.4.25 Panel and/or Segment

The portion of the SCCB cutoff wall started and completed during one rig shift.

1.5 SUBMITTALS

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

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

SD-01 Preconstruction Submittals

All Preconstruction Submittals, except the Preconstruction SCCB Slurry Trial Mix Design Plan and the Preconstruction SCCB Slurry Trial Mix Design Report, must be submitted no later than 30 calendar days after Contract Award. The Preconstruction SCCB Slurry Trial Mix Design Plan must be submitted no later than 7 calendar days after Contract Award and the Preconstruction SCCB Slurry Trial Mix Design Report must be submitted no later than 75 days after Contract Award

SECTION 31 56 13.32 Page 9

SCCB Slurry Cutoff Wall Implementation Plan; G, DO

Equipment and Procedure to Obtain Backfill Bulk Samples of SCCB Backfill Material; G, DO

Preconstruction SCCB Slurry Trial Mix Design Plan; G, DO

Results of SCCB Slurry Trial Mix Designs; G, DO

SCCB Cutoff Wall Quality Control Program; G, DO

Water Quality Test Results; G, DO

Contractor Qualifications; G, DO

Quality Control Laboratory Qualifications; G, DO

Sample Chain of Custody Form for Quality Control and Quality Assurance; G, DO

Cracking and Slurry Leakage Contingency Plan; G, DO

Segment Remediation Plan; G, DO

SD-04 Samples

Bentonite

Portland Cement

Ground Granulated Blast-Furnace Slag Cement

Cutoff Wall Key-in Material

Admixtures;

SD-06 Test Reports

Daily Quality Control Report; G, DO

Weekly Quality Control Report; G, DO

Laboratory Testing Reports; G, DO

Cutoff Wall Key-In Material; G, DO

Slurry Temperature Control Report; G

SD-07 Certificates

Bentonite Powder Manufacturer Test Results; G, DO

Portland and Slag Cement Test Results; G, DO

Admixture Test Results; G, DO

Calibration of Scales and Flow Meters; G, DO

SECTION 31 56 13.32 Page 10

SD-11 Closeout Submittals

Construction Records; G, DO

Construction Documentation; G, DO

Construction Log; G, DO

As-built Drawing; G, DO

1.6 QUALIFICATIONS

1.6.1 Contractor Qualifications

The Contractor's company, subcontractor, joint venture partner (JVP), or merged company (MC) must have experience in cutoff walls used for seepage control within the last ten (10) years from this announcement. Multiple headings on any one contract must be considered as one construction project experience.

Conventional slurry supported cutoff wall construction project experience must include using long-reach excavators or clamshells and include at least two (2) slag cement-cement-bentonite (SCCB) completed cutoff wall projects. For each of the two (2) projects the following cutoff wall standards must have been met to demonstrate sufficient capability:

• A minimum of 50 feet deep;

• A minimum of 24-inches wide;

• A minimum of 500 feet long;

• A maximum permeability of 1x10-6 cm/sec for SCCB cutoff walls at the end of the curing time period specified in the project's contractual requirements; and

• The SCCB cutoff wall must have had a minimum unconfined compressive strength of 50 psi at the end of the curing time period specified in the project's contractual requirements.

Submit Contractor's Qualifications for approval. Example projects provided must include documentation such as contract document excerpts, not to exceed 5 pages, for each project submitted which demonstrate cutoff wall length, width, depth, permeability, and strengths requirements, as appropriate, and laboratory and testing data for cutoff wall permeability and strengths, as appropriate. Additionally, each example project must include a point of contact that may be reached if needed to verify the data. For this contract the following definitions must be used:

Performed the Work: On completed projects, must have prepared trial mix designs and either carried out the mixing and blending operations of the cement-bentonite slurry or provided technical oversight and had overall responsibility for the mixing and blending operations of the cement-bentonite slurry.

1.6.2 Foreman

The foreman must be an employee of the Contractor constructing the cutoff wall (be the Prime Contractor or a Subcontractor) for that specific heading. The foreman must have experience with two cutoff wall projects of the same cutoff wall method, length, depth, long-reach equipment, and constructing cutoff walls in similar soil conditions. The foreman must

SECTION 31 56 13.32 Page 11 also have experience with the various field measuring methods, sampling requirements, and documentation associated with that method of cutoff wall construction.

The candidate must have been employed by the same company and owner for at least 2 years.

The foreman(s) must be on-site whenever the cutoff wall is being constructed.

1.6.3 Qualifications of Slurry Cutoff Wall Specialist and Slurry Cutoff Wall Excavation Equipment Operators

The Contractor must maintain a slurry cutoff wall specialist and equipment operator at the site on a full-time basis while the cutoff wall is being constructed. The primary or alternate employee must be committed to the Contractor for the duration of the project, unless a written release is obtained from the Contracting Officer.

Submit slurry cutoff wall specialist qualifications for approval.

Qualifications must meet the requirements of paragraph SLURRY CUTOFF WALL

SPECIALIST.

Submit slurry cutoff wall excavation equipment operator qualifications for approval. Qualifications must meet the requirements of paragraph SLURRY CUTOFF WALL EXCAVATION EQUIPMENT OPERATOR. If the Contractor utilizes multiple headings, the Contractor must submit qualifications for slurry cutoff wall excavation equipment operators for each heading.

The following information must be submitted to the Government for both the slurry cutoff wall specialist and slurry cutoff wall excavation equipment operators:

a. Name, address, and telephone number of customer and point of contact for projects forming the experience record.

b. Contract number, contract amount, date of award, and date of completion of the project forming the experience.

c. SCCB slurry cutoff wall length and depth.

d. A copy of the portion of the specification requirement from the reference project indicating the required wall performance standards (e.g., permeability, strength) or a letter of reference from the owner for each project submitted that briefly describes the specification requirements.

e. Description of the method of construction and excavation equipment used.

1.6.3.1 Slurry Cutoff Wall Specialist

The slurry cutoff wall specialist must be onsite at all times during the trenching and slurry placement operations and must provide supervision and control of the composition, mixing, placing, and maintenance of the SCCB slurry.

The slurry cutoff wall specialist must be an individual who has had experience with at least three projects and 5 years of experience in all

SECTION 31 56 13.32 Page 12 aspects of SCCB slurry cutoff wall construction which includes, but is not limited to:

a. Controlling composition, mixing, placing, testing, and maintaining the SCCB slurry.

b. Supervision of alignment, verticality, and depth of cutoff walls.

c. The mixing methods required to properly control mixing, properly mix, and place the SCCB slurry as required.

d. Trench excavation and SCCB slurry trench filling procedures.

e. A thorough knowledge of cutoff wall construction equipment and material testing required for slurry cutoff wall construction.

f. Show successful construction of at least three SCCB slurry cutoff walls having similar access constraints and at a minimum as deep and at least as long as this project. Project experience not in North America may be cited, however subject to approval based on verification.

1.6.3.2 Slurry Cutoff Wall Excavation Equipment Operator

Each slurry cutoff wall excavation equipment operator must have a minimum of 5 years of previous successful experience using similar cutoff wall excavation equipment to be used for this Contract in a minimum of two successfully completed projects of similar or greater length and depth.

1.6.4 Trench Quality Control Technician (TQCT)

The TQCT must have a minimum of 2 years of experience including cutoff wall construction and the taking of required measurements of trench geometry, performing trench slurry sampling, and performing trench soundings.

1.6.5 Trench logger

The excavated material from the SCCB slurry cutoff wall excavation is to be described and classified as indicated within this Specification. The description and classification of the excavated material must be performed by a trench logger who must be a degreed geologist or civil engineer with a minimum of five (5) years of experience using ASTM D2488. This individual must work under the responsible charge of either a California Professional Geologist or California Registered Civil Engineer. The experience information must be submitted to the Contracting Officer for review and the Contracting Officer will independently verify classifications as part of its Quality Assurance Program. The information submitted to demonstrate the required experience must include: project name, telephone number of customer and point of contact, date of construction, and a description of the project feature in which classification of material was performed.

1.6.6 Quality Control Engineer

The Quality Control Engineer must be a professional Civil or Geotechnical Engineer licensed in the State of California and must have a minimum of 5 years of construction experience including: cutoff wall construction; a minimum of two SCCB seepage cutoff wall projects; and experience working

SECTION 31 56 13.32 Page 13 as a Cutoff Wall Quality Control Engineer on projects of similar scope, project type, physical size and complexity. The Quality Control Engineer must provide supervision and control of all quality control aspects related to the SCCB seepage cutoff wall. Submit the Quality Control Engineer qualifications as part of the Contractor Qualifications submittal. The Contractor must maintain a Quality Control Engineer at the site on a full-time basis while the cutoff wall is being constructed. The primary or alternate employee must be committed by the Contractor for the duration of the project, unless a written release is obtained from the Contracting Officer. All reports must bear the signature and stamp of the Quality Control Engineer.

1.6.7 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.

1.7 DELIVERY, STORAGE, AND HANDLING

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

1.8 GEOTECHNICAL SITE CONDITIONS

1.8.1 Exploration

Subsurface exploratory borings and cone penetrometer test (CPT) probes have been performed by the Government to evaluate the nature of seepage and determine the character of materials to be excavated. Approximate boring locations and log descriptions are included in the Geotechnical Data Report (GDR) for the convenience of the Contractor. The Government assumes no responsibility for interpretation or deductions 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.

1.8.2 Subsurface Conditions

The levee embankment and subsurface materials encountered during explorations are described in the GDR.

1.8.3 Groundwater

Groundwater at the time of exploratory borings was encountered at the elevations shown on the boring logs. Groundwater levels can be expected to fluctuate in response to variations in rainfall, river stage and irrigation.

1.8.4 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 explorations 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

SECTION 31 56 13.32 Page 14 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.

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 SCCB self-hardening slurry to be used to form the cutoff wall must be suitable for the Project. The Contractor must, if necessary, modify the SCCB 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 PORTLAND AND SLAG CEMENT

Portland cement must be Type I-II and ground granulated blast-furnace slag cement must be grade 120 in accordance with ASTM C150/C150M and ASTM C989/C989M, respectively. All cement must be subject to inspection, sampling, and verification of quality by Contractor quality control testing and Government quality assurance testing. Use of reclaimed cement or cement containing lumps or deleterious matter must not be allowed.

Provide a sample of the portland cement material used within the mix upon request from the Contracting Officer. The sample must consist of a minimum of 50 pounds of each type of proposed portland cement at least 5 days prior to use with certification that it meets ASTM C150/C150M.

Provide a sample of the ground granulated blast-furnace slag cement material used within the mix upon request from the Contracting Officer.

The sample must consist of a minimum of 50 pounds of each type of proposed ground granulated blast-furnace slag cement at least 5 days prior to use with certification that it meets ASTM C989/C989M.

Submit a copy of the portland and slag cement test results from the cement manufacturer for each portland cement and ground granulated blast-furnace slag cement lot shipped to the site and a certificate of compliance stating that the cements complies with all applicable standards.

2.3 BENTONITE

Bentonite must be sodium cation base montmorillonite powder that conforms to API Spec 13A , Section 9. Bentonite must be new, pulverized, high-swelling natural sodium cation montmorillonite (Premium Grade Wyoming-type bentonite or equivalent). Chemically treated bentonite will not be allowed. 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 quality control testing and Government quality assurance testing.

Bentonite not meeting Specifications must be promptly removed from the site and replaced with bentonite conforming to specification requirements at the Contractors expense. Bentonite must be protected from moisture loss during transit and storage.

The contractor must provide a sample of the bentonite material used within

SECTION 31 56 13.32 Page 15 the mix upon request from the Contracting Officer. The sample must consist of a minimum of 10 pounds of the proposed bentonite at least 5 days prior to use with certification that it meets API Spec 13A .

The Contractor must submit bentonite powder manufacturer test results for review statement(s) signed by an authorized official to certify on behalf of the manufacturer of the materials that the products meet the requirements for "bentonite" specified herein. The statement must be dated after the Award of Contract, must state the Contractor's name and address, must name the project and location, and must list the specific requirements that are being certified.

2.4 ADMIXTURES

Admixtures may be used in preparing the SCCB slurry mixture subject to approval by the Government. The Contractor must have on file a written statement from the admixture manufacturer as to the use of any such admixture, its effect on the slurry, its long-term stability, and its effect on the environment. The Government may require the contractor to provide data, studies or other information supporting the use of proprietary and non-proprietary admixtures demonstrating the use of the admixture for its intended purpose does not adversely affect cutoff wall long term performance. Admixtures of the type used in the control of oil-field drilling mud such as thinners, dispersants, and flocculants may be used to control standard properties of the slurry, such as apparent viscosity and filtration characteristics. Admixtures may be added to the water or the slurry to permit efficient use of materials and proper workability. Admixtures beyond those specified in the design mix must be proven in a modified design mix submitted by the Contractor. No admixtures must be added to the SCCB slurry other than those used in the approved mix design. Admixtures must be non-toxic. Contractor must have on file a written statement from the admixture manufacturer regarding the use of the admixture and its effect on the environment. No other admixtures types must be used unless approved.

A copy of the admixtures MSDS and admixture test results from the admixture manufacturer for each lot of fluidifiers, retarders, softening agents, or as approved, shipped to the site and a certificate of compliance stating that the admixture complies with all applicable standards must be furnished by the Contractor to the Government prior to use of the admixture in the work.

2.5 WATER

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.

Submit the water sources used for production and associated pH, hardness, total dissolved solids analysis. Water sources used for production must be the same as those used for trial mix.

2.5.1 Water Standards

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.

SECTION 31 56 13.32 Page 16

Property Pr oper t y Requi r ement Test Met hod pH Value 7.0 +/- 1.0 SM4500 H+B

Total Dissolved Solids <500 ppm SM2540C

Oil, organics, acids, or other deleterious

<50 ppm each API RP 13B-1

Hardness <50 ppm SM2340B

Water with hardness in excess of 50 ppm will be accepted for use by the Government to construct the SCCB cutoff walls based upon performance in the slurry mix as long as the required permeability standards specified herein for the mix are achieved throughout the Project. A record of the water source and associated pH analysis must be furnished by the Contractor.

2.5.2 Hydrants

If hydrants are identified as a water source that the Contractor intends to use: (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 SCCB MIX DESIGN

Mix design for the SCCB slurry must be the responsibility of the Contractor and must take into account the subsurface conditions along the project alignment. The Contractor must prepare and submit a Preconstruction SCCB Slurry Trial Mix Design Plan. The plan must summarize the procedures of the preconstruction SCCB slurry trial mix design. The plan must include a description of materials (including additives), mix proportions (slag cement, cement, bentonite, water, and additives), and test procedures in the proposed SCCB trial mixes. The Preconstruction SCCB Slurry Trial Mix Design Plan must be approved by the Contracting Officer prior to beginning SCCB Slurry trial mix designs and associated testing.

Results of SCCB Slurry Trial Mix Designs must be submitted.

The Contractor must perform a series of trial mix designs based on the approved Preconstruction SCCB Slurry Trial Mix Design Plan to evaluate a range of SCCB slurry mix proportions. The Contractor must prepare a sufficient number of cast samples to support the Contractor's proposed mix design. The minimum number of trial mix designs must be five covering a range of mix constituent percentages. All mix designs must include a minimum of 17 percent by weight of cementitious material over water ratio, range of 70 percent to 80 percent slag cement to cementitious material by weight, and a minimum of 5 percent bentonite of the total mix weight. The test for the trial mix bentonite-water hydrated slurry must include viscosity, density, filtrate loss, and pH. The tests for SCCB slurry must include, but not be limited to, mix proportions by total weight (including any additives used), unconfined compressive strength, hydraulic conductivity, marsh viscosity, density, bleed, temperature and pH of samples at ages of 3, 7, 14, and 28-day. The initial set time of the SCCB slurry must be monitored and recorded.

The Contractor's proposed SCCB slurry mix selected for production work

SECTION 31 56 13.32 Page 17 must undergo a second series of tests in which at least 6 samples with varying percentages of native materials that are representative of the in-situ soil (i.e. size and gradation) are intermixed within the slurry.

The second series of tests for SCCB slurry must include, but not be limited to, mix proportions, unconfined compressive strength, hydraulic conductivity, marsh viscosity, filter press, density, temperature and pH of samples at ages of 3, 7, 14, and 28-day. A minimum of 10 percent of native material must be used. One native material must be 15 percent, while another must be representative of saturated state in which native material are mixed in the fresh SCCB slurry until the native material begins to fall out of suspension. The SCCB slurry selected for production work must have additives mixed with the fresh slurry such that the SCCB slurry will set to a stable and firm wall which will not deform in mass or slough, should it be subject to forces such as localized differential pressures caused by an excavator bucket excavating and pulling material away from an existing segment at a tie-in location. Only those materials approved must be used to fabricate the test specimens. These materials include the cement, slag cement, bentonite, water, admixtures, or other materials.

The Contractor must prepare and submit a Preconstruction SCCB Slurry Trial Mix Design Report. The report must summarize the procedures and results of preconstruction SCCB slurry trial mix designs along with the Contractor's selected mix design for the SCCB slurry. Provided the 14-day test results meet criteria, a draft report may be provided exclusive of the 28-day test results. The report must not be finalized until all test results have been incorporated into the report.

See paragraph, PROPERTIES OF SCCB SLURRY CUTOFF WALL, a and b for hydraulic conductivity and compressive strength test requirements for SCCB Slurry. Only mixes meeting the test requirements may be approved for use.

The Contractor must establish the minimum set time required for the SCCB slurry to harden based on previous experience and the results of the trial mixes.

The initial design mix for the slurry cutoff wall backfill must be selected by the Contractor and approved by the Government based upon the results of the approved Preconstruction SCCB Slurry Trial Mix Design Report. Modifications to the initial design mix must be made only with the approval of the Government. Materials must be thoroughly mixed, and at the time of placement, the slurry must conform to the mixing and placement requirements. The Contractor must not use less than the approved cementitious material to water ratio and bentonite percentage during construction.

The mix designs must include all potential sources of slag cement and portland cement. Sources of these materials not used in the approved mix designs will not be permitted in the cutoff wall construction. Sources of these materials not used in the approved mix design and used in the cutoff wall will be rejected and the panels are to be replaced with material in compliance with those used in the approved mix design. Time extensions will not be granted for variance associated with the slurry and cutoff wall properties specified.

2.7 PROPERTIES OF BENTONITE SLURRY IN MIXING AREA

Testing of slurry properties must be in accordance with API RP 13B-1 .

Before mixing bentonite slurry with cement and slag cement, the bentonite slurry mixture in the mixing area must be required to be hydrated for a

SECTION 31 56 13.32 Page 18 minimum of 8 hours and have the following properties.

SECTION 31 56 13.32 Page 19

Property Pr oper t y Requi r ement Test Met hod

Viscosity > 40 marsh-seconds ASTM D6910

Density > 64 pcf ASTM D4380

Filtrate Loss < 20 cubic cm API RP 13B-1 pH 6.5 to 10 API RP 13B-1

2.8 PROPERTIES OF SCCB SLURRY

The SCCB slurry to support the sides of the excavated trench must consist of a stable colloidal suspension of bentonite, blast-furnace slag cement, portland cement, and water. The SCCB slurry must have the following properties within the trench.

Property Pr oper t y Requi r ement Test Met hod

Density 68 pcf to 80 pcf ASTM D4380 pH 8 to 12 API RP 13B-1

Bleed see note 1 ASTM C940

Viscosity > 35 seconds (see note 1)

API RP 13B-1

Sand content N.A (tested for the record only)

API RP 13B-1 and by field wash sieve

Note 1: The value must be consistent with the mix design.

Sand content must be determined by API sand tube test and also by performing a field wash sieve for separating the minus No. 200 sieve material. The Contractor must have on-site sufficient equipment for measuring the sand content of the slurry. All moist sand extracted from the field wash sieve must be oven dried in a microwave oven. The sand content of the trench slurry must be calculated as follows:

Percentage Sand = Wt. of dry sand/ (total initial weight of slurry sample)

2.9 PROPERTIES OF SCCB SLURRY CUTOFF WALL

The properties of the SCCB slurry cutoff wall must be such that the completed wall will provide a continuous, low permeability barrier between the specified stations and corresponding specified depths, and have the following properties:

a. Hydraulic Conductivity: The SCCB backfill must have a hydraulic conductivity equal to 5x10-7 centimeters per second (cm/sec) or less when measured at 28 days and tested in accordance with ASTM D5084.

b. Unconfined Compressive Strength: The SCCB backfill must have an unconfined compressive strength of at least 30 pounds per square inch (psi) at 3 days when tested in accordance with ASTM D2166. The unconfined compressive strength must be between 100 psi and 450 psi at

SECTION 31 56 13.32 Page 20

28 days when tested in accordance with ASTM D2166.

2.10 MATERIAL STORAGE FACILITY

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

2.11 ENVIRONMENTAL PROTECTION

The raw materials and other supplies used in the construction of the SCCB slurry cutoff wall and any spoil disposed of must be non-hazardous and must comply with the Contract Documents to prevent, and provide for abatement and control of, any environmental pollution arising as a part of the Work.

2.12 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 own expense. Excess SCCB slurry must be disposed of off-site at the Contractor's own expense.

2.13 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 HL-93 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.

2.14 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 for review. Equipment and Procedure to Obtain Backfill Bulk Samples of SCCB Backfill Material will be submitted.

2.14.1 Trench Excavation Equipment

Equipment for excavating the slurry trench must be any type or combination of excavating equipment capable of performing the Work as specified and shown on the Plans. The equipment must be one that reduces live-load surcharge to a level that will maintain stability of the trench. The equipment must be capable of excavating the required minimum width of trench in a single pass of the excavating equipment. The buckets utilized with such equipment may be perforated, tapered, and equipped with bottom-side cutter teeth protruding no more than 6 inches. The excavator bucket teeth must be replaceable with rock excavating teeth and capable of being fitted with a ripper tooth. The bucket must be designed to maintain the width of the trench and to minimize raveling of the trench sides

SECTION 31 56 13.32 Page 21 during use. The equipment must be able to excavate up to 10 feet deeper than the maximum depth shown on the Plans, except that where wall depths are shown to be greater than 80 feet on the Plans this requirement will not apply.

In addition to the excavating equipment, the Contractor must have available on the job site a chopping bit, ripping block, or other suitable devices as required to accomplish the trench excavation to the full required depth. All equipment and any equipment modifications must be reviewed and certified by the equipment manufacturer.

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

2.14.2 SCCB Slurry Mixing Equipment

The equipment used for initial mixing of bentonite and water and subsequent mixing of cement, slag cement, and additives must be capable of mixing the materials into a homogeneous mixture conforming to the contract specification requirements. The slurry mixing plant must be equipped with a high-speed/high-shear, colloidal mixer or a high-velocity/high pressure venturi jet mixer used in conjunction with a high-speed/high-shear centrifugal pump. The plant must be equipped with a mechanically or hydraulically agitated sump and must include pumps, valves, hoses, supply lines, tools, and other equipment and materials required to prepare the slurry and deliver it in a continuous supply from the hydration tanks to the slurry trench. Mixers must be capable of achieving complete dispersion of portland cement, slag cement, bentonite, and additives, and must be capable of continually mixing the hydrated SCCB slurry to provide and maintain a uniform blended slurry. Tanks or other storage facilities for storage of hydrated slurry must be mechanically or hydraulically agitated. The Contractor must have sufficient tanks for storage of the SCCB slurry. Use only Baker tanks, or other approved tanks, to hold fresh mixed slurry.

The slurry mixing equipment must have a controlled weighing system for assuring that the dry and wet constituents of the slurry are properly proportioned. Mixing equipment must have the capability for easy access to the slurry for obtaining fresh samples of any slurry made at the batch plant.

The Contractor is required to calculate and record the percentage by weight of each dry and wet constituent for each batch mixed at the batch plant. The Contractor will check and confirm the weighted or measured percentages of each batch to ensure each batch is proportional to the approved SCCB mix weighted percentages, prior to delivering the batch to the trench.

Manual checks of the SCCB slurry are required at each batch plant, once in the morning (start of shift) and once in the afternoon, and whenever the setting on the batch weighing system is changed.

2.14.3 Field Laboratory Equipment

The 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…