ESBD_File_354873_Construction Specifications_2024-1106.pdf

Construction Specifications for the

North Sewer Force Main –

4th Street to Erskine Street

ODES Project No. 22-23545

December 2023

Revised 3/29/24

Submitted By:

TBPE Firm Registration No. F-760

Construction Specifications for the

North Sewer Force Main -

4th Street to Erskine Street

ODES Project No. 22-23545

In accordance with 137.33 of the Texas Engineering Practice Act and Board Rules, the professional list below are responsible for the specification sections that are listed to the left of their professional seal and/or release note. When more than one professional is shown for certain specification sections, those professionals share joint responsibility for those specification sections.

All Sections listed under Division 2 and Division 3 on the Table of Contents.

December 5, 2023

Revised March 29, 2024

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CONSTRUCTION SPECIFICATIONS

FOR THE

NORTH SEWER FORCE MAIN – 4TH STREET TO ERSKINE STREET

TABLE OF CONTENTS

DIVISION 2: SITE CONSTRUCTION

02260 EXCAVATION SUPPORT AND PROTECTION

02300 EARTHWORK

02317 EXCAVATION AND BACKFILL FOR UTILITIES

02318 BORROW

02320 UTILITY BACKFILL MATERIALS

02326 PIPE JACKING, BORING AND TUNNELING

02349 INSTALLATION OF CARRIER PIPE IN CASING OR TUNNEL LINER PLATE

02665 PIPING, VALVES, AND FITTINGS

DIVISION 3: CONCRETE

03301 CONCRETE VAULTS

03341 PRECAST CONCETE

03360 CONTACT GROUTING

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22-23545

DECEMBER 2023

02260 - Page 1 of 1

EXCAVATION SUPPORT AND PROTECTION

SECTION 02260

EXCAVATION SUPPORT AND PROTECTION

PART 1 - GENERAL

1.1 SUMMARY

A. Section includes temporary excavation support and protection systems.

1.2 PERFORMANCE REQUIREMENTS

A. Design, furnish, install, monitor, and maintain excavation support and protection system capable of supporting excavation sidewalls and of resisting soil and hydrostatic pressure and superimposed and construction loads.

1. Delegated Design: Design excavation support and protection system, including comprehensive engineering analysis by a qualified professional engineer, licensed to practice in the state where the Project will be constructed, using performance requirements and design criteria indicated.

B. As a minimum, the Excavation Support and Protection Plan shall address the following items:

1. Provide details of shoring, bracing, sheet piling, soldier piles and lagging, tie backs, and other support systems and provisions for worker protection from hazards of caving ground.

2. Methods and sequencing of installing excavation support.

3. Proposed locations for excavated materials.

4. Minimum lateral distance from the crest of slopes for vehicles, equipment, and stockpiled materials.

5. Prevent surface water from entering excavations by grading, dikes, or other means.

6. Install excavation support and protection systems without damaging existing buildings, structures, and site improvements adjacent to excavation.

7. Monitor vibrations, settlements, and movements.

1.3 SUBMITTALS

A. Delegated-Design Submittal: For excavation support and protection system indicated to comply with performance requirements and design criteria, including analysis data signed and sealed by the qualified professional engineer, licensed to practice in the state where the Project is constructed, responsible for their preparation.

1.4 PROJECT CONDITIONS

A. Survey Work: Engage a qualified land surveyor or professional engineer to survey adjacent existing buildings, structures, and site improvements; establish exact elevations at fixed points to act as benchmarks. Clearly identify benchmarks and record existing elevations.

END OF SECTION

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SECTION 02300

EARTHWORK

PART 1 - GENERAL

1.1 SUMMARY

A. This Section includes the following:

1. Preparing subgrades for roadways, structures, slabs-on-grade, and related facility work not specified elsewhere.

2. Excavating and backfilling for buildings and structures.

3. Drainage course for slabs-on-grade.

4. Subsurface drainage backfill for walls and trenches.

B. Related Sections:

1. Section 02260 – Excavation and Support Protection

2. Section 02230 – Site Clearing

3. Section 02240 – Dewatering

4. Section 02317 – Excavation, Trenching and Backfilling for Utilities

5. Section 02320 – Utility Backfill Materials

6. Section 02510 – Hot Mix Asphalt Paving

7. Section 02525 – Miscellaneous Roadway Construction

8. Section 02631 – Storm Sewer

1.2 REFERENCES

A. Definitions.

1. Backfill: Soil material or controlled low-strength material used to fill an excavation.

2. Borrow Soil: Satisfactory soil imported from off-site for use as fill or backfill.

3. Completed Course: A course or layer that is ready for next layer or next phase of Work.

4. Drainage Course: Course supporting the slab-on-grade that also minimizes upward capillary flow of pore water.

5. Earthwork: Includes excavation, fill and compaction, grading, and disposal of waste and surplus material.

6. Excavation: Removal of material encountered above subgrade elevations and to lines and dimensions indicated.

a. Authorized Additional Excavation: Excavation below subgrade elevations or beyond indicated lines and dimensions as directed by ENGINEER. Authorized additional excavation and replacement material will be paid for according to Contract provisions for unit prices.

b. Bulk Excavation: Excavation more than 10 feet in width and more than 30 feet in length.

c. Unauthorized Excavation: Excavation below subgrade elevations or beyond indicated lines and dimensions without direction by ENGINEER. Unauthorized excavation, as well as remedial work directed by ENGINEER, shall be without additional compensation.

7. Prepared Ground Surface: Ground surface after completion of required demolition, clearing and grubbing, stripping of topsoil, excavation or fill to grade, and subgrade preparation.

8. Fill: Soil materials used to raise existing grades.

9. Lift: Loose (uncompacted) layer of material.

10. Optimum Moisture Content: Determined in accordance with ASTM Standard specified to determine maximum dry density for relative compaction. Determine field moisture content on basis of fraction passing 3/4-inch sieve.

11. Relative Compaction: Ratio, in percent, of as-compacted field dry density to laboratory maximum dry density as determined in accordance with ASTM D698 and ASTM D1557. Apply corrections for oversize material to either as-compacted field dry density or maximum dry density, as determined by ENGINEER.

12. Rock: Rock material in beds, ledges, unstratified masses, conglomerate deposits, and boulders of rock material that exceed 1 cu. yd. for bulk excavation or 3/4 cu. yd. for footing, trench, and pit excavation that cannot be removed by rock excavating

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equipment equivalent to the following in size and performance ratings, without systematic drilling, ram hammering, ripping, or blasting, when permitted:

a. Excavation of Footings, Trenches, and Pits: Late-model, track-mounted hydraulic excavator; equipped with a 42-inch- wide, maximum, short-tip-radius rock bucket; rated at not less than 138-hp flywheel power with bucket-curling force of not less than 28,090 lbf and stick-crowd force of not less than 18,650 lbf; measured according to SAE J-1179.

b. Bulk Excavation: Late-model, track-mounted loader; rated at not less than 210-hp flywheel power and developing a minimum of 48,510-lbf breakout force with a general-purpose bare bucket; measured according to SAE J-732.

13. Structures: Buildings, footings, foundations, retaining walls, slabs, tanks, curbs, mechanical and electrical appurtenances, or other man-made stationary features constructed above or below the ground surface.

14. Subgrade: Surface or elevation remaining after completing excavation, or top surface of a fill or backfill immediately below subbase, drainage fill, or topsoil materials.

15. Utilities: On-site underground pipes, conduits, ducts, and cables, as well as underground services within buildings.

B. Well-Graded: A mixture of particle sizes that has no specific concentrations or lack thereof of one or more sizes producing a material type which, when compacted, produces a strong and relatively incompressible soil mass free from detrimental voids.

C. Reference Standards.

1. ASTM International:

a. D448 – Standard Method Classification for sizes of Aggregate for Road and Bridge construction.

b. D698 – Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,499 ft-lb.ft3 (600 kN-m/m3))

c. D2487 – Standard Method Classification of Soils for Engineering Purposes (Unified Soil Classification system)

d. D2922 – Standard Test Method for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)

2. American Association of State Highways and Transportation Officials (AASHTO):

a. M288 – Geotextile Specification for Highway Application

3. Texas Department of Transportation: Standard Specifications for Construction of Highways, Streets and Bridges. (TxDOT).

a. TxDOT Item 216 “Proof Rolling”

1.3 SUBMITTALS

A. All submittals shall be in accordance with the Owner’s requirements.

B. Product Data: For the following:

1. Geotextile, if specified on Drawings.

2. Controlled low-strength material, including design mixture.

C. Samples: 12-by-12-inch Sample of subdrainage and/or separation geotextile.

D. Material Test Reports: From a qualified testing agency indicating and interpreting test results for compliance of the following with requirements indicated:

1. Classification according to ASTM D 2487 of each on-site and borrow soil material proposed for fill and backfill.

2. Laboratory compaction curve according to ASTM D 698 or D 1557 for each on-site and borrow soil material proposed for fill and backfill as specified on the drawings.

3. Designated submittals for materials per Section 02320 – Utility Backfill Materials.

E. Pre-excavation Photographs or Videotape: Show existing conditions of adjoining construction and site improvements, including finish surfaces, which might be misconstrued as damage caused by earthwork operations. Submit before earthwork begins.

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1.4 PROJECT CONDITIONS

A. Existing Utilities: If applicable, do not interrupt utilities serving facilities occupied by OWNER or others unless permitted in writing by ENGINEER and then only after arranging to provide temporary utility services according to requirements indicated.

1. Notify ENGINEER not less than two days in advance of proposed utility interruptions.

2. Do not proceed with utility interruptions without ENGINEER'S written permission.

3. Contact utility-locator service for area where Project is located before excavating.

B. Demolish and completely remove from site existing underground utilities as indicated to be removed. Coordinate with utility companies to shut off services if lines are active.

C. Weather Limitations:

1. Material excavated when frozen or when air temperature is less than 32o F shall not be used as fill or backfill until material completely thaws.

2. Material excavated during inclement weather shall not be used as fill or backfill until after material drains and dries sufficiently for proper compaction.

PART 2 - MATERIALS AND PRODUCTS

2.1 SOIL MATERIALS

A. General: Provide borrow soil materials when sufficient satisfactory soil materials are not available from excavations.

B. Satisfactory soils are defined in Paragraphs 2.2 through 2.4.

C. Unsatisfactory Soils: Soil Classification Groups GC, SC, CL, ML, OL, CH, MH, OH, and PT according to ASTM D 2487 or a combination of these groups.

1. Unsatisfactory soils also include satisfactory soils not maintained within 2 percent of optimum moisture content at time of compaction.

2. Depending on the plasticity index (PI) and liquid limits (LL) Soil Classification Groups

GC and SC may be used.

2.2 SELECT FILL

A. Select fill shall consist of soil materials with sufficient plastic fines to minimize water transmission. The select fill should be free of organics and other deleterious materials and should have a maximum particle size no greater than 2 inches. The select fill should meet the USCS classification of either SC (clayey-san), GC (clayey-gravel) or CL(clay of low plasticity, lean clay). Select fill derived from the site must be tested in accordance with Paragraph 1.3.C of this Section, and then approved by the Engineer before use as select fill.

Imported select fill materials must be tested, and then approved by the Engineer before use as select fill.

B. Select fill shall have a liquid limit of 30 or less; plasticity index between 5 and 15.

2.3 SITE FILL

A. Refer to drawings for areas and applications in which placement of site fill is allowable.

B. Satisfactory Soils: ASTM D 2487 Soil Classification Groups GW, GP, GM, SW, SP, and SM or a combination of these groups; free of rock or gravel larger than 3 inches in any dimension, debris, waste, frozen materials, vegetation, and other deleterious matter.

C. Material shall have a liquid limit of 45 or less; plasticity index between 5 and 20; and gradation approximately the limits indicated in Table No. 5.

Table No. 1 Site Fill

Retained on Sieve Percent by Weight

No. 4 Less than 35

No. 200 Less than 65

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2.4 TOP SOIL

A. Material shall be natural friable loam; free of subsoil, roots, grasses, and excessive amount of weeds, stone, and foreign matter.

B. Material shall have a acidity range (pH) between 5.5 to 7.5; an organic matter content between 4 to 25 percent in accordance with ASTM D2974; and a gradation complying with Table No. 6.

Table No. 2 Top Soil

Retained on Sieve Percent by Weight

No. 4 Less than 35

No. 200 Less than 65

2.5 UNCLASSIFIED EXCAVATION

A. All material excavated from site not meeting the requirements for materials specified above.

2.6 FLEXIBLE BASE

A. Flexible base shall conform to TxDOT Item 247 Grade 1 standard, with a plasticity index of 5-12. Materials that meet the latest City of Lubbock Public Works Engineering Minimum Design Standards and Specifications for Item 8.8.02 Flexible Base (Caliche) will be allowed in lieu of TxDOT Item 247. Materials that meet the gradation requirements for TxDOT Item 247 Grade 3 will not be allowed.

2.7 DRAINAGE COURSE AND FILTER MATERIAL

A. Drainage Course: Narrowly graded mixture of washed crushed stone, or crushed or uncrushed gravel; ASTM D 448; coarse-aggregate grading Size 57; with 100 percent passing a 1-1/2-inch sieve and 0 to 5 percent passing a No. 8 sieve.

B. Filter Material: Narrowly graded mixture of natural or crushed gravel, or crushed stone and natural sand; ASTM D 448; coarse-aggregate grading Size 67; with 100 percent passing a 1inch sieve and 0 to 5 percent passing a No. 4 sieve.

2.8 GEOTEXTILES

A. Subsurface Drainage Geotextile: When shown on Drawings, provide non-woven needle-punched geotextile, manufactured for subsurface drainage applications, made from polyolefin or polyesters; with elongation greater than 50 percent; complying with AASHTO M 288 and the following, measured per test methods referenced:

1. Survivability: Class 2; AASHTO M 288.

2. Grab Tensile Strength: 157 lbf; ASTM D 4632.

3. Sewn Seam Strength: 142 lbf; ASTM D 4632.

4. Tear Strength: 56 lbf; ASTM D 4533.

5. Puncture Strength: 56 lbf; ASTM D 4833.

6. Apparent Opening Size: No. 60 sieve, maximum; ASTM D 4751.

7. Permittivity: 0.2 per second, minimum; ASTM D 4491.

8. UV Stability: 50 percent after 500 hours' exposure; ASTM D 4355.

B. Separation Geotextile: If shown on the Drawings, provide woven geotextile fabric, manufactured for separation applications, made from polyolefin or polyesters; with elongation less than 50 percent; complying with AASHTO M 288 and the following, measured per test methods referenced:

1. Survivability: Class 2; AASHTO M 288.

2. Grab Tensile Strength: 247 lbf; ASTM D 4632.

3. Sewn Seam Strength: 222 lbf; ASTM D 4632.

4. Tear Strength: 90 lbf; ASTM D 4533.

5. Puncture Strength: 90 lbf; ASTM D 4833.

6. Apparent Opening Size: No. 60 sieve, maximum; ASTM D 4751.

7. Permittivity: 0.02 per second, minimum; ASTM D 4491.

8. UV Stability: 50 percent after 500 hours' exposure; ASTM D 4355.

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2.9 MATERIAL QUALITY CONTROL

A. Sampling of material stockpiles and material sources shall be in accordance with ASTM D75.

B. Determine Minus 200-Mesh Sieve Test in accordance with ASTM D1140.

C. Determine optimum soil moisture content in accordance with ASTM D698.

D. Perform gradation analysis in accordance with ASTM C136 for:

1. Coarse and fine aggregate, natural gravel, crushed stone for foundation, sand, select fill, impervious clay fill, earth fill, and topsoil.

E. Perform abrasion testing in accordance with ASTM C131 or ASTM C535.

1. Coarse and fine aggregate and when requested by ENGINEER for natural gravel and crushed stone for foundation.

F. Soundness testing in accordance with ASTM C88.

1. Coarse and fine aggregate and when requested by ENGINEER for natural gravel and crushed stone for foundation.

G. Deleterious materials determination in accordance with ASTM C40, C117, and C142.

1. Coarse and fine aggregate and when requested by ENGINEER for natural gravel and crushed stone for foundation

H. Determine liquid limit and plasticity index in accordance with ASTM D4318.

1. Sand for particles passing No. 8 sieve, select fill, impervious clay fill, and earth fill.

I. Determine pH of topsoil in accordance with ASTM D2974.

J. Determine permeability (hydraulic gradient) in accordance with ASTM D5084 and percent dispersion in accordance with ASTM D4221 of impervious clay fill materials.

2.10 CONTAMINATION TESTING AND CERTIFICATION

A. When materials are suspected of contamination, the CONTRACTOR shall arrange and pay for the services of an EPA approved laboratory to perform a toxic contaminant scan of composite borrow material samples in accordance applicable federal, state and local regulations.

B. Soil materials derived from the excavation of underground petroleum storage tanks shall not be used as fill on Project.

PART 3 - EXECUTION

3.1 PREPARATION

A. Protect structures, utilities, sidewalks, pavements, and other facilities from damage caused by settlement, lateral movement, undermining, washout, and other hazards created by earthwork operations.

B. Preparation of subgrade for earthwork operations including removal of vegetation, topsoil, debris, obstructions, and deleterious materials from ground surface is specified in Section 02230 — Site Clearing.

C. Protect and maintain erosion and sedimentation controls, which are specified in Section 02230 — Site Clearing, during earthwork operations.

D. Provide excavation support and protection in accordance with Section 02260 — Excavation Support and Protection.

E. Excavation, trenching, and backfilling work for utilities shall be accomplished in accordance with Section 02320 — Excavation, Trenching and Backfilling for Utilities.

3.2 DEWATERING

A. Prevent surface water and ground water from entering excavations, from ponding on prepared subgrades, and from flooding Project site and surrounding area.

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B. Protect subgrades from softening, undermining, washout, and damage by rain or water accumulation.

1. Reroute surface water runoff away from excavated areas. Do not allow water to accumulate in excavations. Do not use excavated trenches as temporary drainage ditches.

2. Where shown on the drawings, install a dewatering system, specified in Section 02240

— Dewatering, to keep subgrades dry and convey ground water away from excavations. Maintain until dewatering is no longer required.

3.3 EXPLOSIVES

A. No explosives of any kind will be allowed on site at any time.

3.4 EXCAVATION, GENERAL

A. Excavations shall be observed by the Geotechnical Engineer to make sure that the proper bearing material has been reached. The excavations shall be checked for size and observed by the Geotechnical Engineer to make sure that loose material has been removed prior to concrete placement.

B. Unclassified Excavation: Excavate to subgrade elevations regardless of the character of surface and subsurface conditions encountered. Unclassified excavated materials may include rock, soil materials, and obstructions. No changes in the Contract Sum or the Contract Time will be authorized for rock excavation or removal of obstructions.

1. If excavated materials intended for fill and backfill include unsatisfactory soil materials and rock, replace with satisfactory soil materials from an approved quarry. Submit quarry test results to ENGINEER for approval prior to use.

2. Remove rock to lines and grades indicated to permit installation of permanent construction without exceeding the following dimensions:

a. 24 inches outside of concrete forms other than at footings.

b. 12 inches outside of concrete forms at footings.

c. 6 inches outside of minimum required dimensions of concrete cast against grade.

d. Outside dimensions of concrete walls indicated to be cast against rock without forms or exterior waterproofing treatments.

e. 6 inches beneath bottom of concrete slabs on grade.

3.5 EXCAVATION FOR STRUCTURES

A. Excavate to specified elevations and dimensions within a tolerance of plus or minus 1 inch. If applicable, extend excavations a sufficient distance from structures for placing and removing concrete formwork, for installing services and other construction, and for inspections. Submit quarry test results to ENGINEER for approval prior to use.

1. Excavations for Footings and Foundations: Do not disturb bottom of excavation.

Excavate by hand to final grade just before placing concrete reinforcement. Trim bottoms to required lines and grades to leave solid base to receive other work. Refer to Drawings for treatment of subgrade, the addition of a concrete seal slab, installation of vapor barrier, or other work required prior to placement of footings and foundations.

2. Pile Foundations: Stop excavations 6 to 12 inches above bottom of pile cap before piles are placed. After piles have been driven, remove loose and displaced material.

Excavate to final grade, leaving solid base to receive concrete pile caps.

3. Excavation for Underground Tanks, Basins, and Mechanical or Electrical Utility Structures: Excavate to elevations and dimensions indicated within a tolerance of plus or minus 1 inch. Do not disturb bottom of excavations intended as bearing surfaces.

B. Undercutting:

1. When objectionable material not suitable for foundation or subgrade material is present in locations for subgrade or foundation construction, as determined by ENGINEER, undercut material to the depth and extent as directed and backfill with suitable material.

2. Place fill material in uniform layers and compact as specified for soil backfill and fills.

3. Dispose of undercut materials off-site.

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3.6 SUBGRADE PREPARATION AND INSPECTION

A. Notify ENGINEER when excavations have reached required subgrade.

B. If ENGINEER determines that unsatisfactory soil is present, continue excavation and replace with compacted backfill or fill material as directed.

C. Subgrade shall be prepared and meet the requirements of the latest City of Lubbock Public Works Engineering Minimum Design Standards and Specifications for Item 8.8.01 Subgrade.

D. Authorized additional excavation and replacement material will be paid for according to Contract provisions for unit prices.

E. Reconstruct subgrades damaged by freezing temperatures, frost, rain, accumulated water, or construction activities, as directed by ENGINEER, without additional compensation.

3.7 UNAUTHORIZED EXCAVATION

A. Fill unauthorized excavation under foundations or wall footings by extending bottom elevation of concrete foundation or footing to excavation bottom, without altering top elevation. Lean concrete fill, with 28-day compressive strength of 2500 psi, may be used when approved by ENGINEER. Fill unauthorized excavations under other construction or utility pipe as directed by ENGINEER.

3.8 STORAGE OF SOIL MATERIALS

A. Stockpile borrows soil materials and excavated satisfactory soil materials without intermixing.

Place, grade, and shape stockpiles to drain surface water. Cover to prevent windblown dust.

1. Stockpile soil materials away from edge of excavations. Do not store within drip line of remaining trees.

2. Confine stockpiles to within easements, right-of-way, and approved areas. Do not obstruct roads or streets.

3.9 BACKFILL

A. Place and compact backfill in excavations promptly, but not before completing the following work as applicable:

1. Construction below finish grade including, where applicable, subdrainage, damp proofing, waterproofing, and perimeter insulation.

2. Surveying locations of underground utilities for Record Documents.

3. Testing and inspecting underground utilities.

4. Removing concrete formwork.

5. Removing trash and debris.

6. Removing temporary shoring and bracing, and sheeting.

7. Installing permanent or temporary horizontal bracing on horizontally supported walls.

8. Leakage tests for structures.

B. Place backfill on subgrades free of mud, frost, snow, or ice.

3.10 SOIL FILL

A. Plow, scarify, bench, or break up sloped surfaces steeper than 1 vertical to 4 horizontal so fill material will bond with existing material.

B. Place and compact fill material in layers to required elevations as follows:

1. Under grass and planted areas, use satisfactory soil material.

2. Under walks and pavements, use satisfactory soil material.

3. Under steps and ramps, use select or granular fill, unless otherwise shown on

Drawings.

4. Under building slabs, use select, fill, unless otherwise shown on drawings.

C. Place soil fills on subgrades free of mud, frost, snow, or ice.

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3.11 SOIL MOISTURE CONTROL

A. Uniformly moisten or aerate subgrade and each subsequent fill or backfill soil layer before compaction to within 2 percent of optimum moisture content, if not specified on the Drawings or in the Geotechnical Report.

1. Do not place backfill or fill soil material on surfaces that are muddy, frozen, or contain frost or ice.

2. Remove and replace, or scarify and air dry otherwise satisfactory soil material that exceeds optimum moisture content by 2 percent and is too wet to compact to specified dry unit weight.

3. Do not allow the moisture content in the subgrade and layers below the slab base to fall below the optimum moisture content.

B. Vapor Barrier: Place polyethylene sheeting below the concrete slabs. If the subgrade underlying the vapor barrier contains sharp or angled particles, then a layer of cushion sand (1 to 2-inches thick) should be placed in contact with the sheet to provide protection against puncture. Note that the elevation and thickness of the slab shall not be changed to adjust for the layer of cushion sand.

3.12 COMPACTION OF SOIL BACKFILLS AND FILLS

A. Place backfill and fill soil materials in layers not more than 6 inches in loose depth for material compacted by heavy compaction equipment, and not more than 4 inches in loose depth for material compacted by hand-operated tampers.

B. Place backfill and fill soil materials evenly on all sides of structures to required elevations, and uniformly along the full length of each structure.

C. Compact soil materials to not less than the following percentages of maximum dry unit weight according to ASTM D 698, if not specified on the Drawings:

1. For all excavations, backfills, or embankments, 95 percent.

D. Avoid over compaction of the subgrade and any other layers of backfill or fill soil.

3.13 GRADING

A. General: Uniformly grade areas to a smooth surface, free of irregular surface changes.

Comply with compaction requirements and grade to cross sections, lines, and elevations indicated.

1. Provide a smooth transition between adjacent existing grades and new grades.

2. Cut out soft spots, fill low spots, and trim high spots to comply with required surface tolerances.

B. Site Grading: Slope grades to direct water away from buildings and to prevent ponding.

Finish subgrades to required elevations within the following tolerances:

1. Lawn or Unpaved Areas: Plus or minus 1-inch.

2. Walks: Plus or minus 1 inch.

3. Pavements: Plus or minus 1/2 inch.

3.14 SUBSURFACE DRAINAGE

A. When shown on the Drawings, provide subsurface drainage in accordance with the following paragraphs.

B. Sub-drainage Pipe: Specified in Section 02240 – Dewatering.

C. Subsurface Drain: Place subsurface drainage geotextile around perimeter of sub-drainage trench. Place a 6 inch course of filter material on subsurface drainage geotextile to support sub-drainage pipe. Encase sub-drainage pipe in a minimum of 12 inches of filter material, placed in compacted layers 6 inches thick, and wrap in subsurface drainage geotextile, overlapping sides and ends at least 6 inches. Compact each filter material layer with a minimum of two passes of a plate-type vibratory compactor.

D. Drainage Backfill: Place and compact filter material over subsurface drain, in width indicated, to within 12 inches of final subgrade, in compacted layers 6 inches thick. Overlay drainage

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backfill with one layer of subsurface drainage geotextile, overlapping sides and ends at least 6 inches.

1. Compact each filter material layer with a minimum of two passes of a plate-type vibratory compactor.

2. As shown on the Drawings, place and compact impervious fill over drainage backfill in

6 inch thick compacted layers to final subgrade.

3.15 DRAINAGE COURSE

A. Place drainage course on subgrades free of mud, frost, snow, or ice.

B. On prepared subgrade, place and compact drainage course under cast-in-place concrete slabs-on-grade as follows:

1. Install sub-drainage geotextile on prepared subgrade according to manufacturer's written instructions, overlapping sides and ends.

2. Place drainage course 6-inches or less in compacted thickness in a single layer.

3. Place drainage course that exceeds 6-inches in compacted thickness in layers of equal thickness, with no compacted layer more than 6-inches thick or less than 3 inches thick.

4. Compact each layer of drainage course to required cross sections and thicknesses to not less than 95 percent of maximum dry unit weight according to ASTM D 698.

3.16 FIELD QUALITY CONTROL

A. Allow testing agency to inspect and test subgrades and each fill or backfill layer. Proceed with subsequent earthwork only after test results for previously completed work comply with requirements.

B. Footing Subgrade: At footing subgrades, at least one test of each soil stratum will be performed to verify design bearing capacities. Subsequent verification and approval of other footing subgrades may be based on a visual comparison of subgrade with tested subgrade when approved by ENGINEER.

C. Testing agency will test compaction in accordance with ASTM D 2922 and moisture content in accordance with ASTM of soils. Tests for both compaction and moisture content will be performed at the following locations and frequencies:

1. Building Slab Areas: At subgrade and at each compacted fill and backfill layer, at least

1 test for every 2500 sq. ft., but in no case fewer than 2 tests at each layer.

2. Foundation Wall Backfill: At each compacted backfill layer, at least 1 test for each 100 feet or less of wall length, but no fewer than 2 tests.

3. Pavement Areas: For subgrade, flexible caliche base, and at each compacted fill or backfill layer, at least 1 test for every 5,000 sq. ft.

D. When testing agency reports that subgrades, fills, or backfills have not achieved degree of compaction specified, scarify and moisten or aerate, or remove and replace soil to depth required; re-compact and retest until specified compaction is obtained.

3.17 PROTECTION

A. Protecting Graded Areas: Protect newly graded areas from traffic, freezing, and erosion.

Keep free of trash and debris.

B. Repair and reestablish grades to specify tolerances where completed or partially completed surfaces become eroded, rutted, settled, or where they lose compaction due to subsequent construction operations or weather conditions.

1. Scarify or remove and replace soil material to depth as directed by ENGINEER;

reshape and re-compact.

C. Where settling occurs before Project correction period elapses, remove finished surfacing, backfill with additional soil material, compact, and reconstruct surfacing.

1. Restore appearance, quality, and condition of finished surfacing to match adjacent work, and eliminate evidence of restoration to greatest extent possible.

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EARTHWORK

3.18 DISPOSAL OF SURPLUS AND WASTE MATERIALS

A. Disposal: Remove surplus satisfactory soil and waste material, including unsatisfactory soil, trash, and debris, and legally dispose of it off OWNER'S property.

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SECTION 02317

EXCAVATION AND BACKFILL FOR UTILITIES

PART 1 - GENERAL

1.1 SUMMARY

A. Related Sections:

1. Section 02260 – Excavation Support and Protection

2. Section 02300 – Earthwork

3. Section 02318 – Borrow

4. Section 02320 – Utility Backfill Materials

5. Section 02871 – Sanitary Sewer Piping

6. Section 03301 – Concrete Vaults

1.2 DEFINITIONS

A. Pipe Foundation: Suitable and stable native soils that are exposed at the trench subgrade after excavation to depth of bottom of the bedding as shown on the Drawings, or foundation backfill material placed and compacted in over-excavations.

B. Pipe Bedding: The portion of trench backfill that extends vertically from top of foundation up to a level line at bottom of pipe, and horizontally under 1/3 of the pipe O.D.

C. Haunching: The material placed on either side of pipe from the foundation to the springline of the pipe for rigid wall pipe, and horizontally from one trench sidewall to opposite sidewall, excluding the bedding section as shown on the plans. For flexible wall pipe, the haunching material extends to a minimum of 12” above the top of the pipe.

D. Initial Backfill: The portion of trench backfill that extends vertically from the top of haunching or cement stabilized backfill up to a level line immediately below pavement subgrade, and horizontally from one trench sidewall to opposite sidewall.

E. Pipe Embedment: The portion of trench backfill that consists of bedding, haunching and initial backfill.

F. Trench Zone: The portion of trench backfill that extends vertically from top of pipe embedment up to a line immediately below pavement subgrade or up to final grade when not beneath pavement.

G. Backfill: Suitable material meeting specified quality requirements, placed and compacted under controlled conditions.

H. Ground Water Control Systems: Installations external to trench, such as well points, eductors, or deep wells. Ground water control includes dewatering to lower ground water, intercepting seepage which would otherwise emerge from side or bottom of trench excavation, and depressurization to prevent failure or heaving of excavation bottom.

I. Seepage: Water intrusion from groundwater into an excavation or trench via the sidewalls and floor of the excavation or trench such that sidewall material and excavated floor material are not displaced by hydraulic pressure or flow, and the flow rate of groundwater intrusion is such that the excavation or trench will accumulate more than a 3-inch depth in the floor of the excavation or trench in a 24-hour period if not removed by pumping, bailing or other methods, or not intercepted by an external groundwater dewatering system.

J. Surface Water Control: Diversion and drainage of surface water runoff and rain water away from trench excavation. Rain water and surface water accidentally entering trench shall be controlled and removed as a part of excavation drainage.

K. Excavation Drainage: Removal of surface water in trench by sump pumping or other approved means.

L. Trench Conditions are defined with regard to the stability of trench bottom and trench walls of pipe embedment zone. Maintain trench conditions that provide for effective placement and

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compaction of embedment material directly on or against undisturbed soils or foundation backfill, except where structural trench support is necessary.

1. Dry Stable Trench: Stable and substantially dry trench conditions exist in pipe embedment zone as a result of typically dry soils or achieved by ground water control (dewatering or depressurization) for trenches extending below ground water level.

2. Stable Trench with Seepage: Stable trench in which ground water seepage is controlled by excavation drainage.

a. Stable Trench with Seepage in Clayey Soils: Excavation drainage is provided in lieu of or to supplement ground water control systems to control seepage and provide stable trench subgrade in predominately clayey soils prior to bedding placement.

b. Stable Wet Trench in Sandy Soils: Excavation drainage is provided in the embedment zone in combination with ground water control in predominately sandy or silty soils.

3. Unstable Trench: Unstable trench conditions exist in the pipe embedment zone if ground water inflow or high water content causes soil disturbances, such as sloughing, sliding, boiling, heaving or loss of density.

M. Subtrench: Subtrench is a special case of benched excavation. Subtrench excavation below trench shields or shoring installations may be used to allow placement and compaction of foundation or embedment materials directly against undisturbed soils. Depth of a subtrench depends upon trench stability and safety as determined by the Contractor.

N. Over-Excavation and Backfill: Excavation of subgrade soils with unsatisfactory bearing capacity or composed of otherwise unsuitable materials below top of foundation as shown on Drawings, and backfilled with foundation backfill material.

O. Foundation Backfill Materials: Natural soil or manufactured aggregate of controlled gradation, to control drainage and material separation. Foundation backfill material is placed and compacted as backfill to provide stable support for bedding.

P. Trench Safety Systems include both protective systems and shoring systems as defined in Section 02260 – Excavation Support and Protection.

Q. Trench Shield (Trench Box): A portable worker safety structure moved along the trench as work proceeds, used as a protective system and designed to withstand forces imposed on it by cave-in, thereby protecting persons within the trench. Trench shields may be stacked if so designed or placed in a series depending on depth and length of excavation to be protected.

R. Shoring System: A structure that supports sides of an excavation to maintain stable soil conditions and prevent cave-ins, or to prevent movement of the ground affecting adjacent installations or improvements.

1.3 REFERENCES

A. ASTM D 558 - Test Methods for Moisture-Density Relations of Soil Cement Mixtures.

B. ASTM D 698 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12400 ft-lbf/ft3 (600 kN-m/m3))

C. ASTM D 1556 - Test Method for Density in Place by the Sand-Cone Method.

D. ASTM D 1557 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3))

E. ASTM D 2487 - Classification of Soils for Engineering Purposes.

F. ASTM D 2922 - Test Method for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth).

G. ASTM D 3017 - Test Method for Water Content of Soil and Rock in Place by Nuclear Methods (Shallow Depth).

H. ASTM D 4318 - Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.

I. TxDOT Tex-101-E - Preparation of Soil and Flexible Base Materials for Testing.

J. TxDOT Tex-110-E - Determination of Particle Size Analysis of Soils.

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K. Federal Regulations, 29 CFR Part 1926, Standards-Excavation, Occupational Safety and Health Administration (OSHA).

1.4 SCHEDULING

A. Schedule work so that pipe embedment can be completed on the same day that acceptable foundation has been achieved for each section of pipe installation, manhole, or other structures.

1.5 SUBMITTALS

A. Submittals shall be in conformance with the Owner’s requirements.

B. Submit a written description for information only of the planned typical method of excavation, backfill placement and compaction, including:

1. Sequence of work and coordination of activities.

2. Selected trench widths.

3. Procedures for foundation and embedment placement, and compaction.

4. Procedure for use of trench boxes and other pre-manufactured systems while assuring specified compaction against undisturbed soil.

C. Submit a ground and surface water control plan in accordance with requirements in this Section.

D. Submit backfill material sources and product quality information in accordance with requirements of Section 02320 — Utility Backfill Materials.

E. Submit record of location of utility as installed, referenced to survey control points. Include locations of utilities encountered that are not shown on Drawings or rerouted for the convenience of the Contractor. Give stations, NAD 83 state plane coordinates, NAVD 88 elevations, inverts, and gradients of installed utility.

F. Submit all field density tests of trench backfill.

G. Submit laboratory density compaction curves for each material to be used as backfill.

1.6 TESTS

A. Perform backfill material source qualification testing in accordance with requirements of Section 02320 – Utility Backfill Materials.

B. Perform field density tests of trench backfill representative of each 500 linear feet of trench and each one-foot of lift thickness.

C. Once within pavement subgrade perform at least one test at subgrade and at each compacted layer for every 5000 sf or less of paved areas, but in no case fewer than three tests in the prepared area.

D. The Owner will perform his own check of field densities at random intervals at Owner’s expense for passing tests. Failing tests will be charged to the Contractor.

PART 2 - PRODUCTS

2.1 EQUIPMENT

A. Perform excavation with hydraulic excavator or other equipment suitable for achieving the requirements of this Section.

B. Use only hand-operated tamping equipment until a minimum cover of 12 inches is obtained over pipes, conduits, and ducts. Do not use heavy compacting equipment until adequate cover is attained to prevent damage to pipes, conduits, or ducts. Do not use vibratory equipment until 5 feet of cover over pipes, conduits and ducts is obtained. Do not use vibratory equipment if adjacent structures are affected.

C. Use trench shields or other protective systems or shoring systems which are designed and operated to achieve placement and compaction of backfill directly against undisturbed native soil.

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2.2 MATERIAL CLASSIFICATIONS

A. Bedding, Embedment and Trench Zone Backfill Materials: Conform to classifications and product descriptions of Section 02320 — Utility Backfill Materials.

B. Bedding shall be “concrete” sand or pea gravel.

C. Embedment shall be crushed rock.

D. Trench backfill native soil material.

PART 3 - EXECUTION

3.1 PREPARATION

A. Establish traffic control to conform with requirements of Section 01570 – Maintenance and Control of Traffic.

B. Perform work to conform with applicable safety standards and regulations. Employ a trench safety system as specified in Section 02260 – Excavation Support and Protection.

C. Immediately notify the agency or company owning any existing utility line which is damaged, broken, or disturbed. Obtain approval from the Owner and agency for any repairs or relocations, either temporary or permanent.

D. Remove existing pavements and structures, including sidewalks and driveways, to conform with requirements of Section 02221 - Removing Existing Pavements.

E. Maintain permanent benchmarks, monumentation, and other reference points. Unless otherwise directed in writing, replace those which are damaged or destroyed.

3.2 PROTECTION

A. The Contractor shall locate all existing underground lines of which he has been advised, whether or not they are shown on the Drawings, sufficiently in advance of trenching operations to prevent any damage thereto.Verification of location, size and burial depth of existing utilities shall be the complete responsibility of the Contractor.

B. The Contractor shall protect trees, shrubs, lawns, existing structures, and other permanent objects outside of grading limits and within the grading limits as designated on the Drawings.

C. Trench digging machinery may be used to make the trench excavations except in places where operation of same would cause damages to pipelines, fences or other existing structures either above or below ground; in such instances hand methods shall be employed.

D. Contractor shall protect and support above-grade and below-grade utilities which are to remain.

E. Contractor shall restore damaged permanent facilities to pre-construction conditions, at the Contractors expense, unless replacement or abandonment of facilities are indicated on the Drawings.

F. Contractor shall implement measures to minimize erosion of trenches. Do not allow water to pond in trenches. Where slides, washouts, settlements, or areas with loss of density or pavement failures or potholes occur, repair, re-compact, and pave those areas at no additional cost to Owner.

G. The Contractor is responsible for notifying pipeline and cable utility owners of his intention of crossing their utility no less than seven days prior to crossing the utility.Coordinate vertical separation requirements with the utility owners and any other special construction considerations. Notify the Engineer of required changes in the vertical profile shown on the Drawings prior to constructing these changes.

3.3 EXCAVATION

A. Perform excavation work so that pipe, conduit, and ducts can be installed to depths and alignments shown on the Drawings. Avoid disturbing surrounding ground and existing facilities and improvements.

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B. In situations where benching of trench is required for lowering excavator below grade, minimum bench width should be 22’-0” to allow the excavator to make a 90° pivot unless Contractor chooses to “walk” the excavator on a ramp into and out of the trench.

C. All excavated material shall be piled in a manner that will not endanger the work or existing structures.Excess trench excavation, not used for backfilling, shall be disposed of by Contractor, and at contractor's expense.

D. Blasting will not be permitted on this project.

E. Salvage topsoil in unpaved areas for later re-introduction into surface of trench. In park and roadside ditch areas, topsoil will be considered to be the soil above the uppermost calcium carbonate caliche layer. In rangeland and cultivated farm land, topsoil shall be considered to be the uppermost three feet of soil, or less if a calcium carbonate caliche layer is encountered at less than three-foot depth. Depth of topsoil may vary. Excavate topsoil and keep separate from other excavated soil. Excavate with smooth-lip excavator bucket if necessary to avoid intermixing with caliche and undesirable soils. Stockpile topsoil separately from other excavated materials.

F. Use sufficient trench width or benches above the embedment zone for installation of well point headers or manifolds and pumps where depth of trench makes it uneconomical or impractical to pump from the surface elevation. Provide sufficient space between shoring cross braces to permit equipment operations and handling of forms, pipe, embedment and backfill, and other materials.

G. Upon discovery of unknown utilities, badly deteriorated utilities not designated for removal, or concealed conditions, discontinue work at that location. Notify the Engineer and obtain instructions before proceeding.

H. Shoring of Trench Walls.

1. Install Special Shoring in advance of trench excavation or simultaneously with the trench excavation, so that the soils within the full height of the trench excavation walls will remain laterally supported at all times.

2. For all types of shoring, support trench walls in the pipe embedment zone throughout the installation. Provide trench wall supports sufficiently tight to prevent washing the trench wall soil out from behind the trench wall support.

3. Unless otherwise directed by the Engineer, leave sheeting driven into or below the pipe embedment zone in place to preclude loss of support of foundation and embedment materials. Leave rangers, walers, and braces in place as long as required to support sheeting, which has been cut off, and the trench wall in the vicinity of the pipe zone.

4. Employ special methods for maintaining the integrity of embedment or foundation material. Before moving supports, place and compact embedment to sufficient depths to provide protection of pipe and stability of trench walls. As supports are moved, finish placing and compacting embedment.

5. If sheeting or other shoring is used below top of the pipe embedment zone, do not disturb pipe foundation and embedment materials by subsequent removal. Maximum thickness of removable sheeting extending into the embedment zone shall be the equivalent of a 1-inch-thick steel plate. Fill voids left on removal of supports with compacted backfill material.

6. Wherever necessary to prevent caving, the trench shall be adequately supported as required by the Drawings and Specifications. The Contractor is entirely responsible for assuring that trenches are adequately supported to protect both his workmen and the public.

I. Use of Trench Shields. When a trench shield (trench box) is used as a worker safety device, the following requirements apply:

1. Make trench excavations of sufficient width to allow shield to be lifted or pulled freely, without damage to the trench sidewalls.

2. Move trench shields so that pipe, and backfill materials, after placement and compaction, are not damaged nor disturbed, nor the degree of compaction reduced.

3. When required, place, spread, and compact pipe foundation and bedding materials beneath the shield. For backfill above bedding, lift the shield as each layer of backfill is placed and spread. Place and compact backfill materials against undisturbed trench walls and foundation.

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4. Maintain trench…