SECTION_31_56_23_-_Soil-Cement-Bentonite_Cutoff_Wall_R2_0004.pdf

BUREAU OF INDIAN AFFAIRS OGLALA DAM SPILLWAY AND OUTLET WORKS

OGLALA DAM SPILLWAY AND OUTLET WORKS SECTION 31 56 23

JUNE 2023 SOIL-CEMENT-BENTONITE CUTOFF WALL

FOR BID REV 2 PAGE 1 OF 12

SECTION 31 56 23

SOIL-CEMENT-BENTONITE CUTOFF WALL

GENERAL

1.01 SCOPE OF WORK

A. This Section includes furnishing plant, labor, material, and equipment for construction of a mix-in-place continuous low permeability Soil-Cement-Bentonite (SCB) Cutoff Wall along the embankment crest from Station EM 7+50 to EM 22+20.

B. The cutoff wall shall be constructed using a specialized high-torque in-situ deep soil mixing (DSM) equipment with the reach and torque capacity to meet the intended project depths, soil conditions, and specification tolerances.

C. The low permeability cutoff wall will be constructed such that the horizontal permeability is 1 x 10-6 centimeters per second (cm/sec) or lower and shall have a minimum unconfined compressive strength (UCS) of 50 pounds per square inch (psi) after 28 days of curing.

The cutoff wall shall have no gaps, holes, defects, or zones that exhibit a permeability greater than 1 x 10-6 cm/sec.

D. The materials used in the construction of the barrier wall shall include a mixture of water, specified bentonite, and Ground Granulated Blast-Furnace Slag (Slag) cement and/or

Portland cement (blend of Slag cement and Portland cement), as appropriate to achieve the performance criteria. CONTRACTOR shall be responsible for developing the design mix, which will be verified by the Quality Control program. For bidding purposes only, a minimum additive rate has been provided in this Section. CONTRACTOR shall consider in their bid any and all waste or excess materials required to achieve the minimum additive rates for the final barrier wall material.

E. The in-situ mixing methods that may be proposed may include either single or multiple auger type equipment, a horizontal mounted drum cutter wheel system (such as a Cutter

Soil Mixer) (CSM), or a “one-pass” trencher system provided that any of these methods can meet the technical specification and performance criteria for the project. Alternative methods of open slurry trench and backfill will not be considered for this project.

F. Transport to the site, mobilize and employ all equipment, materials, products, tools, services, supervision and labor required to complete the SCB Cutoff Wall. Includes but is not limited to limited to:

Preparing all work plans and pre-installation submittals.

Providing all materials and sitework necessary to create a suitable working platform for the equipment to construct the SCB Cutoff Wall.

Providing installation equipment, tooling, and support equipment.

BUREAU OF INDIAN AFFAIRS SECTION 31 56 23

FOR BID REV 2 PAGE 2 OF 12

Providing equipment to pump and store water used in mixing.

Providing means and methods to sample and test the mixed materials prior to curing.

Providing measures to protect the dam and reservoir from contamination by cutoff wall mixing fluids or equipment fluids.

Providing removal and disposal of excess SCB materials.

G. The locations and depths of the cutoff wall may be changed in the field by the BIA

Representative, based on actual conditions encountered.

1.02 REFERENCE STANDARDS

A. The following guidance documents apply to the testing, materials and methods referenced within these Specifications.

B. ASTM International (ASTM)

ASTM C150 Specification for Portland Cement

ASTM C989 Standard Specification for Ground Granulated Blast-Furnace Slag for Use in Concrete and Mortars

ASTM D422 Particle-Size Analysis of Soils

ASTM D1633 Unconfined Compressive Strength of Soil-Cement

ASTM D4380 Density of Bentonite Slurries

ASTM D4832 Preparation and Testing of Soil-Cement Slurry Test Cylinders

ASTM D5084 Hydraulic Conductivity Using a Flexible Wall Permeameter

C. Additional methods or alternate methods shall be described in the Work Plan.

1.03 RESPONSIBILITIES

A. CONTRACTOR will be responsible for completing the work in accordance with industry safety and performance standards.

B. CONTRACTOR will be responsible for recording details on the SCB Cutoff Wall including verification of the top of embedment layer (claystone bedrock) elevation and bottom of wall elevation.

C. CONTRACTOR will be responsible for collecting samples of the SCB material and providing QC testing results.

D. The BIA Representative will be responsible for reviewing submittals and, if necessary, changes to the plans and specifications based on field conditions.

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E. The BIA Representative shall be responsible for overseeing the SCB Cutoff Wall installation, monitoring CONTRACTOR’s work for compliance with project requirements, and ensuring that all the QC/QA requirements are met.

1.04 JOB SITE CONDITIONS

A. Information used to develop the wall profile is contained in the Geotechnical Data Report, Oglala Dam Subsurface Investigation, prepared by GEI Consultants, Inc., dated December

2021. The transition zone between the soil layers and the corresponding strata elevations defined in this report should be considered approximate. CONTRACTOR should account for this possible adjustment in the field in their bid price.

B. The barrier wall shall extend through both fill and native soils and embed into bedrock, as shown on the profile drawings.

1.05 SUBMITTALS

A. Shop Drawings

Submit a Detailed Cutoff Wall Work Plan to the BIA Representative for review and approval no less than 1 month prior to mobilization to the site. Include the following:

a. Project schedule.

b. Site use and layout of equipment set-up and storage areas, haul roads, locations of stockpiles for excavated embankment soils, riprap to be placed, disposal of excess SCB Cutoff Wall materials and other site use plans.

c. Sample Weekly Activity Report and Daily Record Log.

d. Proposed mix design, including compatibility with water on site.

1) Submit formulas for mix ratio of soil, cement, bentonite and water by volume, as selected by performing a bench scale test.

e. Detailed step-by-step procedure for installation of the cutoff wall and collecting

SCB samples.

1) Installation method and equipment to be used.

2) Sampling frequency and techniques.

3) Procedures to follow in case of a fluid loss event.

4) Procedures to follow in case an artesian condition is encountered.

5) Procedures for verification of embedment layer elevation confirmation.

6) Waste disposal.

Qualifications of key personnel including resumes of the cutoff wall installation crew meeting the criteria in the Qualifications Section of this specification.

Provisions to control artesian conditions and prevent loss of material should artesian conditions be encountered.

Safety Data Sheets (SDS) sheets for all chemicals to be used on site including cement and bentonite.

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B. Administrative

Provide weekly activity reports to the BIA Representative. These shall include:

a. Maker and manufacturer’s model number designation of installation equipment.

b. Method of sampling and testing locations, by depth.

c. Date, time of day, dam centerline station reference and cutoff wall depth when mixing, sampling and standby operations were performed.

d. Depths to an accuracy of 0.1-foot for bottom depth of the cutoff wall at a minimum 10-foot interval along the cutoff wall alignment or per column/panel, as applicable to the construction method being used. Depth information obtained should be sufficient to record all apparent changes in conditions (e.g., voids, geologic variations, obstructions). Also, provide depth for each sample interval.

e. Down time for maintenance and/or repair.

f. Daily Records – During construction of the cutoff wall, CONTRACTOR shall submit daily records to the BIA Representative and copies to the COR, within 2 working days of each work day. The daily records shall be reviewed and signed by CONTRACTOR or a designated representative. The records are to include tabulated reports of overall project progress including location of cutoff wall sections installed and a drawing showing completed areas. CONTRACTOR’s quality control reporting requirements shall also be included as part of the daily records.

C. Quality Control

CONTRACTORS’s quality control reports per each day of installation shall include:

a. Record of cutoff wall depth

b. Cutoff wall mixing data including:

1) addition rate vs depth

2) volume

3) pump volume vs time

4) inclination (in two directions)

5) speed of mixing tool

6) general rig parameters

7) Final Report and As-built Profile: The following information shall be submitted to the BIA Representative within three weeks of the completion of

Work. Copies of all daily reports, production logs, laboratory test results, record of cutoff wall depth achieved during construction including, admixture rates and volumes, and total materials used at the site. The project log depths shall be used to generate an as-built profile of the cutoff wall, as constructed. Also included in the final report shall be records of:

Soil-Cement Bentonite Mixes: A record of SCB mix material quantities, properties, and mix adjustments made during construction. Location of samples for laboratory

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testing shall be noted. Submit any mix modification reports throughout construction for COR review and approval.

A record of quality control samples, tests, and all test results.

Verification Testing Results: Verification testing shall be the performed by

CONTRACTOR’s quality control team in cooperation with the BIA Representative to ensure the quality and performance of the SCB Cutoff Wall materials.

1.06 SCHEDULING AND SEQUENCE

A. Locate and protect existing instrumentation locations prior to beginning work activities.

B. Prepare the work platform surface.

C. All cutoff wall construction activities shall take place in the presence of the BIA

Representative. Provide a minimum of 5 days’ notice before planning to proceed with field activities.

1.07 QUALIFICATIONS

A. CONTRACTOR and/or its Subcontractor shall:

Have a minimum of 10 years of similar mix-in-place soil-cement and soil-cement-bentonite experience in dams and levees.

Evidence of CONTRACTOR experience shall include references from at least three similar and successful projects constructed over the last 5 years and employment of an experienced engineer with at least 10 years of experience in in-situ cutoff wall construction on at least three similar projects shall plan and direct the methods of the work. Project descriptions shall include at a minimum the dimensions of work staging area, a detailed work plan, mix design development, material preparations, and detailed equipment descriptions. This evidence will help validate that CONTRACTOR will have sufficient competent experienced personnel and proven methods and equipment to carry out the operations specified.

The company name, key contact, and qualifications of CONTRACTOR’s off-site laboratory shall be submitted. The laboratory will have previous experience with soil mixed materials, experienced laboratory technicians, and modern laboratory testing equipment.

B. The BIA Representative reserves the right to reject personnel based on incomplete credentials or insufficient qualifications.

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PRODUCTS

2.01 EQUIPMENT

A. All equipment shall be consistent with the Work Plan. Unsafe, hazardous or technically inadequate equipment shall be removed and replaced at no cost or delay to the Project

Schedule or to the AGENCY. Deviations from the approved Work Plan must first be submitted to the BIA Representative for review and approval and then to the COR for the same. All equipment shall be kept in good working condition at all times and repaired or replaced when deficiently operative at no additional cost to the AGENCY. Equipment not meeting the production rates or work quality noted in the Work plan shall be replaced by

CONTRACTOR at no additional cost to the AGENCY.

2.02 MATERIALS

A. All materials shall conform to the approved Work Plan. All material submittals shall be approved prior to use, and only approved materials shall be incorporated into the Work.

Deviations from the approved Work Plan must first be submitted to the BIA Representative for review and approval, and then to the COR for the same.

B. For bidding purposes, CONTRACTOR shall assume the following materials to construct the cutoff wall. A final mix design shall be developed by CONTRACTOR in collaboration with the BIA Representative, after the Contract has been awarded. Costs for gathering site samples and laboratory services for developing the final SCB mix designs should be included in CONTRACTOR’s bid.

Bentonite: Bentonite shall be added to the soil at a minimum rate of 20 kg/m3.

Bentonite used shall be pulverized (powder) premium grade sodium cation montmorillonite and shall meet the most current API Standard 13A “API specification for Oil-Well Drilling Fluid Materials”. Bentonite shall be tested for compatibility with water intended to be used in mixing and with groundwater as the permeant in hydraulic conductivity testing prior to acceptance.

90/10 Slag Cement/Portland Cement (blended product): 90/10 Slag/Portland cement blend shall be added to the soil at a minimum rate of 120 kg/m3.

a. Materials shall be blended together at a 90 percent Slag cement to 10 percent

Portland (by weight) to meet this specification. Materials may be blended either on-site or off-site to meet this blended composition. Verification of the final blended material weights and ratios shall be provided by CONTRACTOR.

b. Slag and Cement shall meet the material requirements of Section 03 30 00 –

Cast-In-Place Concrete.

Water: CONTRACTOR shall utilize water meeting the requirements of Section

03 30 00 – Cast-In-Place Concrete. CONTRACTOR shall bear all costs for access and use and/or treatment of the water supply. The water shall be clean, fresh, and free from excessive oil, acid, alkali, organic matter, or other harmful substances.

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Additives: Admixtures of the type used in the control of oil-field drilling muds such as softening agents, dispersants, retarder, or plugging or bridging agents may be added to the water or the suspension to permit efficient use of bentonite. The BIA

Representative must approve, and advise, of all additives prior to use.

SCB Mix Performance:

a. The material formed by mixing the suspension with the in-situ soil shall have a permeability of 1 x10-6 cm/sec or less and shall have a minimum unconfined compressive strength (UCS) of 50 pounds per square inch (psi) after 28 days of curing using the test methods outlined in Part 3.

EXECUTION

3.01 ACCESS, UTILITY CLEARANCE, TRAFFIC CONTROL

A. Provide low ground-pressure (less than 1,250 psf. To be used as basis of bid. Final pressure to be checked during design.) equipment to limit loads on the dam crest.

B. Contact South Dakota 811 or 800-781-7474 for utility clearance at least one week prior to mobilizing to site.

3.02 PROTECTION OF SITE

A. GENERAL

Maintain all property in a condition acceptable to the COR. Promptly repair any damage caused by the Work to a condition acceptable to the COR.

Excavations in excess of work platform preparation are prohibited. Any excavations deemed necessary by CONTRACTOR, not shown on the Drawings, shall be submitted and reviewed by the BIA Representative.

Prevent surface runoff from causing erosion on the embankment slopes.

3.03 CONSTRUCTION

A. The SCB Cutoff Wall shall be constructed using CONTRACTOR’s chosen and COR’s approved in-situ mixing processes to the depths, grades, and cross sections indicated on the drawings. The cutoff wall shall be essentially vertical with a pattern of overlapping columns, or continuous, as applicable to the method, and shall extend through the overburden and key into the claystone bedrock to the elevations shown on the profile drawings. A generalized description of the soil profile through which the cutoff wall is to be constructed is provided on the Contract Drawings as well as on the boring logs that are included in the site’s geotechnical report.

3.04 TEST SECTION

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A. CONTRACTOR shall complete a 100 lineal-foot SCB test section as the first 100 feet of placement. Location to be at CONTRACTOR’s discretion within the wall alignment.

B. Design test section to demonstrate the proposed construction methods, to meet the performance criteria of the mix design, and to demonstrate proposed sampling and cutoff wall geometry verification measurement procedures.

C. A minimum of four in-situ wet grab samples of mixed SCB material shall be collected from the test section and sent to CONTRACTOR’s laboratory for strength and hydraulic conductivity testing. Provide wet grab sample material for the COR’s Quality Assurance, as requested by the BIA Representative.

3.05 ALIGNMENT

A. CONTRACTOR shall accurately stake the alignment of the proposed cutoff wall, as shown on the drawings.

B. CONTRACTOR shall establish two sets of control lines by survey outside the limits of the work. The center of the cutoff wall shall be measured (or established by offset control lines) from these control lines based on a drawing of the overlap pattern. Alternatively, a multiple laser grid system or other remote survey device may be used.

3.06 DEPTH

A. The depth of the cutoff wall shall be determined by the lines and grades shown on the

Drawings and based on pre-construction confirmation soil borings completed by

ENGINEER. The Drawings include soil borings completed for design but are not sufficient for confirmation of the bedrock elevation. Pre-installation delineation for verification of the bedrock depth will be conducted at a minimum of 50-foot spacing.

B. The total depth of penetration shall be electronically measured and recorded on 10-foot intervals or for each column/panel installed depending on the installation method used.

The depth of the cutoff wall shall be measured from the bottom of the mixing tool or at the center of the apex if a CSM tool is used.

3.07 OBSTRUCTIONS AND PRACTICAL REFUSAL CRITERIA

A. Provide proposed means and methods for constructing continuous cutoff wall extending to the target bottom of wall elevation if obstructions such as boulders are encountered.

B. CONTRACTOR may be required to remediate obstructions by removal (excavation).

C. Practical Refusal Criteria shall be defined as 6-inches of depth penetration within one hour for auger-type mixing equipment. For trencher-type equipment, Practical Refusal Criteria shall be defined as refusal of the equipment to pass through the obstruction.

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D. Meeting the practical refusal criteria must be verified from penetration speed, rotational speed, the vertical load from the mixing tool (crowd force), mixing energy, and power consumption needed for mixing tool penetration.

E. The refusal criteria can be adjusted during the field test section, if approved by the BIA

Representative.

3.08 WATER AND SWELL/SPOIL MANAGEMENT

A. Obtain water for mixing operations. Draw water from the reservoir, provided the operation does not introduce any contaminants into the reservoir.

B. Provide all equipment and storage facilities necessary to collect water.

C. Wasted fluids and cuttings must be contained on site and disposed of or reused on-site, if approved by the BIA Representative.

D. CONTRACTOR shall manage stockpiles of excess materials resulting from the SCB construction. These materials shall be spread out on the platform in a manner so that they may cure or be amended (if needed). Spoils are not suitable for reuse as backfill on the dam embankment. The responsibility of management, collection, stockpiling, treatment, temporary storage, handling, and disposal of the swell/spoils lies solely with

CONTRACTOR.

E. CONTRACTOR to assume removal of all swell/spoils from site.

3.09 SAMPLE COORDINATION

A. Provide SCB samples to the BIA Representative.

B. Assist BIA Representative in loading, transporting, and unloading samples to a central location on the site if necessary.

3.10 CUTOFF WALL COMPLETION

A. Upon completion of mixing, allow a minimum of 48 hours for SCB curing before fill is placed on top of the cutoff wall.

Observe SCB settlement in the cutoff wall after 48 hours.

If SCB settles less than 1 foot, backfill with tamped sand or gravel to the ground (work platform) surface.

If the SCB settles more than 1 foot, backfill with additional SCB or grout to the ground surface. Grout mix to be approved by the BIA Representative.

B. Upon completion of the SCB Cutoff Wall construction, the surface shall be cleaned of all waste spoils prior to embankment fill placement.

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C. Remove the work platform and finish the crest of the dam as required in the Drawings after completion of the SCB Cutoff Wall.

3.11 TOLERANCES

A. The following tolerances shall apply to the SCB Cutoff Wall dimensions and construction.

The Cutoff Wall shall be essentially vertical. The working platform and/or rig shall be leveled to be plumb within 0.5% of vertical.

Cutoff wall verticality shall not deviate more than 0.5% for the entire length of the cutoff wall.

The depth shall be measured from a controlled measuring point near the surface to the bottom of the mixing auger/tool; measurement shall be converted to NAVD 88 elevations.

The cutoff wall may vary from the designed alignment to accommodate equipment limitations if approved by the COR.

The center of the cutoff wall shall be constructed within 3 inches of the designated alignment location.

Construction will not be permitted when the air temperature is below 20o F or when severe weather conditions may compromise the quality of the work.

The volume of mix materials shall be calculated and checked based on daily completion of production logs.

3.12 IN-SITU SAMPLING TOOL

A. A special sampling tool will be provided by CONTRACTOR for obtaining samples of the wet, mixed soil, at depth in the cutoff wall. The sampler shall consist of a weighted chamber, which can be opened and closed from the surface to obtain mixed soil and suspension. The sampler may be attached to the cutoff wall mixing equipment or supported by a second machine.

3.13 QUALITY ASSURANCE AND QUALITY CONTROL

A. Quality Control shall be the primary responsibility of CONTRACTOR. CONTRACTOR shall perform or supervise all operations, measurements, and tests. CONTRACTOR shall prepare and maintain detailed records of the mixes, materials, tests, and completion records.

B. A summary of the required tests is shown in Table 1. The primary aspects of Quality

Control Program are specified herein.

C. Continuity and Depth

CONTRACTOR shall be responsible for demonstrating to the satisfaction of the BIA

Representative that the work is continuous, and the minimum specified depth is

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achieved. The BIA Representative will be available onsite to verify these measurements.

Material:

a. All permanent materials shall be certified by the manufacturer to comply with the specified standard. Certificates of Compliance with the specification shall accompany each truckload of materials received on site.

Soil Mixed Material:

a. Wet samples of the soil mixed materials shall be obtained with the in-situ sampler and tested for slump in accordance with ASTM C143 and temperature immediately upon retrieval of a bulk in-situ wet soil-mixed sample. The wet sample should be screened with a ½ inch screen and then formed into test cylinders and tested for permeability using ASTM Method D 5084 and unconfined compressive strength (UCS) using ASTM method D 5102 in accordance with frequency and cure times shown in Table 1. Each bulk sample shall consist of at least four test cylinders made once every day or 500 cubic yards. Duplicate and/or spilt samples shall be made available to the COR’s

Quality Assurance (QA) team. CONTRACTOR shall coordinate with the BIA

Representative to collect additional QC samples, if requested.

Documentation:

a. All quality control records, tests and inspections documentation shall be maintained by CONTRACTOR and available for review by the COR and BIA

Representative. CONTRACTOR shall record all measurements and test results performed by CONTRACTOR’s Quality Control.

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Table 1: DSM Quality Control Testing Plan

Property Requirement Minimum Test

Frequency Test Method Comment

Bentonite Powder

a. Certification By Manufacturer 1 per shipment API 13A, Section 10 Wyoming type

(90 bbl/ton) untreated, organic free

Cement Powder

a. Certification

(Portland cement)

By Manufacturer 1 per shipment ASTM C150 Portland Type I or I-II

b. Certification

(Slag cement)

By Manufacturer 1 per shipment ASTM C989 GGBFS Grade 120 I

c. 90/10 Slag cement

(blended)

90 % Slag /

10 % Portland

(by weight)

1 per batch certified scale record

Water for Slurry Mixing

a. pH 6 to 9 1 per source Hach Kit or laboratory

(9040B)

Site Source

b. Hardness < 250 ppm 1 per source Hach Kit or laboratory

(SM 2340C)

c. Alkalinity < 250 ppm 1 per source Hach Kit or laboratory

(SM 2320B)

d. Total Dissolved

Solids

< 1500 ppm 1 per source Hach Kit or laboratory

(SM 2540C)

Initial Bentonite Slurry

a. Viscosity < 30 sec. 4 per shift API RP 13B-1 Each AM prior to

Production

b. Density > 1.012 gm/cc 4 per shift API RP 13B-1 2 % slurry concentration

c. pH of Slurry > 7.5 4 per shift Hach Kit

d. Bentonite content B/W > 1% <3% 1 per batch Record Batch records

Cement-Bentonite Grout

a. Density > 1.2 gm/cc 4 per shift API RP 13B-1

b. pH of Grout > 10 4 per shift Hach Kit

c. Temperature of Grout <20o above ambient 4 per shift Thermometer

d. Grout Injection Rate Record per DSM panel Record DSM Recording Data

Soil-mixed Materials

a. Admixture Injection Rates

Bentonite > 20 kg/m3 1 per 500 LF calculations DSM Recording Data and

Material Usage 90/10 Slag cement 120 kg/m3 1 per 500 LF calculations

b. Slump 4 > 10 inches 1 per 50 CYS (first 150 LF)

1 per 500 CYS

(after 150 LF)

ASTM C143 Wet sample

c. Temperature <20o above ambient 1 per 50 CYS (first 150 LF)

1 per 500 CYS

(after 150 LF)

Thermometer Wet sample

d. Permeability < 1 x 10-6 cm/sec 1 per 50 CYS (first 150 LF)

1 per 500 CYS

(after 150 LF)

ASTM D5084 Cured for 28 days

e. UCS > 50 psi 1 per 50 CYS (first 150 LF)

1 per 500 CYS

(after 150 LF)

ASTM D1633 Cured for 28 days

END OF SECTION