Skip Navigation LinksHome > Departments > Public Works > Engineering Division > Construction Specifications > Excavating, Backfilling & Compacting

Excavating, Backfilling & Compacting

Excavating, Backfilling & Compacting

(Section 02220)

PART 1 GENERAL

1.01 WORK INCLUDED

A. Contractor shall provide all materials, labor, equipment, transportation and other items required to perform excavation, backfilling and compaction Work as indicated or as required to accomplish Work of other sections of these specifications. All excavation, backfilling and compaction Work shall be in accordance with applicable regulations and as specified herein.

B. Excavating, backfilling and compaction includes, but is not limited to the following:

     1. Preparation

     2. Excavation, backfilling and compaction

     3. Dewatering and/or runoff control measures

     4. Trench shoring

     5. Clean up, protection, maintenance

1.02 RELATED WORK

A. Section 01005 - Administrative Provisions

     1. Warranty requirements.

A. Section 02590 - Restoration of Existing Improvements

     1. Restoration of surfaces or facilities lost, damaged or displaced as a result of Work included in this section.

B. Section 02665 - Potable Water Distribution Systems

     1. Trench excavation, bedding, backfill and compaction requirements.

C. Section 02730 - Sanitary Sewage Systems

     1. Trench excavation, bedding, backfill and compaction requirements.

1.03 REFERENCES

A. The applicable provisions of the latest editions of the References listed below shall govern the Work covered under this Section, unless there is a conflict between said References and the requirements of this Section. In the case of such a conflict, the requirements of this Section shall apply.

B. Utah Occupational Safety and Health Division (UOSHD).

C. American Association of State Highway and Transportation Officials (AASHTO):

D. American Society for Testing and Materials (ASTM)

E. Midvale City Corporation Standard Construction Details

1.04 SUBMITTALS

A. Submit evidence of materials conformance with applicable requirements as well as these specifications.

1.05 QUALITY ASSURANCE

A. Comply with federal, state, and local codes and regulations.

B. All working conditions shall be in accordance with the "Utah Occupational Safety and Health Division", Safe Practices for Excavation & Trenching Operations, latest edition, or other Laws or Regulations which apply.

C. Salt Lake County requirements shall govern for all work in Salt Lake County road right-of-ways:

     1. All work shall conform to the applicable standards, regulations, and requirements of the Salt Lake County Public Works Department.

     2. Permits shall be obtained and paid for by the Contractor.

     3. License and Permit Bond, without cancellation clause, in an amount and form prescribed by the Salt Lake County Department of Public Works, shall be provided by the Contractor in connection with his excavations in Salt Lake County Right-of-Way.

D. Utah Department of Transportation requirements shall govern for all work in Utah Department of Transportation highway right-of-ways:

     1. All work shall conform to the applicable standards, regulations and requirements of the Utah Department of Transportation, including the Specifications for Excavation on State Highways.

     2. Permits shall be obtained and paid for by the Contractor.

     3. License and Permit Bond, without cancellation clause, in an amount and form prescribed by the Utah Department of Transportation, shall be provided by the Contractor in connection with his excavations on Utah Department of Transportation Right-of-Way.

E. Utah Department of Transportation requirements in Salt Lake County Roads:

     1. Where reference is made to Utah Department of Transportation standards in these Specifications for work in Salt Lake County roads, the work shall conform to the applicable Utah Department of Transportation standards.

F. Extended Warranty Period for work in Salt Lake County and Utah Department of Transportation roadways, shall apply.

1.06 DELIVERY, STORAGE AND HANDLING

Not Used

1.07 PROJECT CONDITIONS

Not Used

PART 2 PRODUCTS

2.01 MANUFACTURERS

A. Materials suppliers shall provide, upon request, verification of a consistent record of meeting or exceeding materials or performance standards as specified herein.

2.02 FOUNDATION MATERIALS

A. All foundation materials shall be free from alkali, salt, and petroleum products, roots, sod, limbs, and other vegetative matter, slag, cinders, ashes and rubbish, or other material that in the opinion of the Engineer may be objectional or deleterious.

B. Undisturbed soil foundation material:

     1. Shall be natural trench bottom soil unless unable to adequately support pipe or structures.

     2. Shall not be lumpy or frozen.

C. Gravel:

     1. Shall be hard, durable, broken stone or slag.

     2. Shall be graded within the following limits:

          Sieve % Passing
          1" 100
          3/4" 85-100
          1/2" 20-40
          No. 4 10-20

2.03 BEDDING MATERIALS

A. Sand Bedding Material:

     1. Shall be free from alkali, salt, and petroleum products, roots, sod, limbs, and other vegetative matter, slag, cinders, ashes and rubbish, or other material that in the opinion of the Engineer may be objectional or deleterious.

     2. Graded within the following limits:

          Sieve % Passing
          3/4" 100
          No. 4 80-100
          No. 10 30-50
          No. 40 10-30
          No. 200 0-15

2.04 BACKFILL MATERIALS

A. Granular backfill:

      1. Shall be readily compactable and shall be free from alkali, salt, and petroleum products, roots, sod, limbs, and other vegetative matter, slag, cinders, ashes and rubbish, or other material that in the opinion of the Engineer may be objectional or deleterious.

     2. Graded within the following limits:

          Sieve % Passing
          3 inch 100
          No. 10 50 max.
          No. 40 30 max.
          No. 200 15 max.

     3. May be select material from excavation if it will meet all requirements of granular backfill, including compaction requirements as specified for type of surface improvement above trench.

B. Excavated Soil Backfill Material:

     1. Shall be free from alkali, salt, and petroleum products, roots, sod, limbs, and other vegetative matter, slag, cinders, ashes and rubbish, or other material that in the opinion of the Engineer may be objectional or deleterious.

     2. Shall be select material from excavation, with no particle larger than 4 inches in diameter.

     3. Use on-site materials only if specified compaction requirements can be met.

PART 3 EXECUTION

3.01 EXAMINATION

A. It shall be the Contractor's sole responsibility to locate all (whether or not shown on the Drawings) existing water, sanitary sewer, storm drain, and gas lines, electrical and telephone conduit and other underground utilities with their existing house service connections, and all other underground structures in order that no damage or loss of service will result from interference with existing lines.

B. Review all available drawings, notes, and information on the location of these underground lines and structures in determining the location of the existing facilities.

C. Have an electronic pipe finder on the job at all times and mark all lines on the road ahead of the excavating machine.

D. Blue Stakes Location Center shall be contacted 48 hours before any excavation is commenced. Phone 532-5000 for assistance.

E. Mark with paint any existing cracks on concrete along which work will take place, in order to determine after the construction is completed whether such damage was caused by the operations of the Contractor or had occurred previously. Any concrete showing unmarked cracks upon completion of construction shall be evidence of damage caused by the Contractor, and shall be replaced or repaired to the satisfaction of the Owner of the damaged concrete, at the Contractor's sole expense.

F. All fences removed for excavation shall be returned to their original condition except that damaged portions will be replaced with new fencing at the Contractor's expense.

G. Obtain all required permits.

3.02 METHODS AND PROCEDURES

A. General Requirements

     1. All gas, sanitary sewer, storm drain, water and other pipelines, flumes and ditches of metal, wood or concrete, underground electrical conduits and telephone cable, and all walks, curbs, and other improvements encountered in excavating trenches carefully shall be supported, maintained and protected from injury or interruption of service until backfill is complete and settlement has taken place.

     2. If any existing facility is damaged or interrupted, promptly after becoming aware thereof and before performing any Work affected thereby, identify the owner of such existing facility, and give written notice thereof to that owner and the Owner and Engineer. Indemnify the Owner from any and all damages resulting from damaged facilities.

     3. All damage, injury or loss resulting from lack of adequate sheeting, bracing, and shoring shall be the responsibility of the Contractor; and the Contractor shall effect all necessary repairs or reconstruction resulting from such damage.

     4. The trenches shall not be backfilled until the utilities systems as installed conform to the requirements of the Drawings and Specifications. Where, in the opinion of the Engineer, damage is likely to result from withdrawing sheeting, the sheeting shall be left in place.

     5. Trenches shall be backfilled to the proper surface with material as shown or specified. Trenches improperly backfilled shall be reopened to the depth required for correction, then refilled and compacted as specified, or the condition shall be otherwise corrected as approved.

     6. Care shall be exercised so that when backfilling is complete and settlement has taken place, all existing pipes, flumes, ditches, conduits, cables, walks, curbs, and other improvements will be on the same alignment and grade as they were before work commenced.

     7. Compaction shall be the responsibility of the Contractor. He shall select the methods to be used and carefully perform the work of backfilling and compaction so as to prevent damage to new or existing piping. Any new or existing piping damaged during the Contractor's work shall be replaced as directed by the Engineer with new piping.

3.03 INSTALLATION

A. Excavation

     1. Excavation for pipe lines, concrete valve boxes, manholes and appurtenant structures shall include the work of removing all earth, sand, gravel, quicksand, stone, loose rock, solid rock, clay, shale, cement, hardpan, boulders, and all other materials necessary to be moved in excavating the trench for the pipe; maintaining the excavation by shoring, bracing, and sheeting or well pointing to prevent the sides of the trench from caving in while pipe laying is in progress; and removing sheeting from the trench after pipe has been laid.


     2. Trench support system shall be suitable for the soil structure, depth of cut, water content of soil, weather conditions, superimposed loads, vibration. Contractor may select one of the following methods of ensuring the safety of workers in the trench, as approved by the Utah State Industrial Commission or its safety inspectors:

          a. Sloping sides of trench to the angle of repose at which the soil will remain safely at rest.

          b. Shoring trench sides by placing sheeting, timber shores, trench jacks, bracing, piles, or other materials to resist pressures surrounding the excavation.

          c. Using a movable trench box built-up of steel plates and a heavy steel frame of sufficient strength to resist the pressures surrounding the excavation.

     3. Trenches shall be of the necessary width for proper laying of pipe. Care shall be taken not to overexcavate. The bottom of the trenches shall be accurately graded to provide uniform bearing and support for each section of the pipe along the entire length of the barrel of the pipe.

     4. Trenches shall be excavated to the depths shown on the Drawings, including any required allowances for the sewer rock foundation, when required, and for other pipe bedding requirements.

     5. Minimum cover over the top of the pipe, including any paving, shall be as follows:

          a. Water supply piping: 3.5 feet minimum from finish grade.

     6. Grading of trenches shall be performed to avoid interference of water and sewer lines with other underground utilities and structures:

         a. Water supply piping: Unless otherwise indicated, trenches shall be graded to avoid high points with the necessity of placing vacuum and relief valves in the water lines.

     7. The width of trench, measured at the top of the pipe, shall be as narrow as possible but not wider than 15 inches on each side of sewer or water pipe.

     8. Excavation for manholes, concrete valve boxes, and similar structures shall be sufficient to leave at least 12 inches in the clear between the outer surfaces and the embankment or timber that may be used to hold and protect the banks.

     9. Excess materials shall be hauled away from the construction site or otherwise disposed of by the Contractor as approved by the Engineer.

B. Backfilling

      1. Materials for trench backfill shall be as shown on the Drawings.

      2. Pipe bedding:

          a. Consists of preparing an acceptable pipe foundation, excavating the pipe groove in the prepared foundation and backfilling from the foundation to 12 inches above the top of the pipe. All piping shall be protected from lateral displacement and possible damage resulting from impact or unbalanced loading during backfilling operations by being adequately bedded.

          b. Pipe foundation: Shall consist of natural soil in the bottom of the trench, or a built-up foundation if conditions so warrant. Wherever the trench subgrade material does not afford a sufficiently solid foundation to support the pipe and superimposed load, and where groundwater must be drained, the trench shall be excavated below the bottom of the pipe to such depth as may be necessary, and this additional excavation filled with clean, compacted sewer rock.

          c. A pipe groove shall be excavated in the pipe foundation to receive the bottom quadrant of the pipe so that the installed pipe will be true to line and grade. Bell holes shall be dug after the trench bottom has been graded. Bell holes shall be excavated so that only the barrel of the pipe bears on the pipe foundation.

          d. Pipe bedding from pipe foundation to 12 inches above top of pipe: Materials shall be deposited and compacted in layers not to exceed 8 inches in uncompacted depth. Deposition and compaction of bedding materials shall be done simultaneously and uniformly on both sides of the pipe. All bedding materials shall be placed in the trench with hand tools or other approved method in such a manner that they will be scattered alongside the pipe and not dropped into the trench in compact masses. Materials used shall be as shown in the Typical Trench Section in the Drawings and as specified in Part 2.

     3. Each lift shall be evenly spread and moistened or dried by disk harrowing or other means so that the required density will be produced.

     4. Backfill around valves with Granular Backfill Material.

C. Compaction

      1. Backfill Compaction Requirements:

          a. Under pavements, or other surface improvements, the average density shall be 96% of laboratory maximum density with no individual test lower than 92% of the laboratory maximum density, as determined by AASHTO Designation T-180 (ASTM D-1557).

          b. In shoulders and other unimproved areas, the average density shall be 90% of laboratory maximum density with no individual test lower than 86% of the laboratory maximum density, as determined by AASHTO Designation T-180 (ASTM D-1557).

     2. Compaction shall be performed in strict accordance with the manufacturer's recommendations for each type of pipe.

     3. Mechanical compaction: Shall be accomplished by the use of sheeps-foot rollers, pneumatic tire rollers, vibrating rollers, or other mechanical tampers of a size and type necessary to achieve the required degree of compaction.

D. Dewatering

     1. The Contractor shall do all pumping, shall build all drains and do all the work necessary to keep the trench and pipes free from water during the progress of the work.

     2. In wet trenches, a channel shall be kept open along the side of the pipe for conducting the water to a sump hole, from which it shall be pumped out of the trench. No water shall be allowed to enter the pipe.

3.04 PROTECTION

A. Provide barricades and restrict access as appropriate to prevent damage to Work in place.

B. Contractor shall be responsible for protection of Work in place against displacement, damage, or loss until Owner's acceptance. Any work and subsequently damaged, lost or displaced shall be repaired or replaced to the Owner's satisfaction at no additional cost.

3.05 CLEANING

A. Thoroughly clean, rake, wash, flush or sweep as required to clean adjacent improvements of materials covered as part of this Work prior to submitting for Owner's acceptance.

B. Contractor shall provide all labor, equipment, materials and other items as required to perform clean up as required by the Owner, adjacent property owners and other jurisdictions.

C. Finish grading of areas affected by this Work shall be required as part of clean up.

D. The roadway including shoulders, slopes, ditches, and borrow pits shall be smoothly trimmed, and shaped by machinery, or other satisfactory methods, to the lines, grades and cross-sections, as established, and shall be so maintained until accepted. Any surplus material not suitable for spreading along the road to widen the existing shoulder or raise the grade shall be disposed of as specified above.

3.06 TESTING

A. The Owner shall employ a testing laboratory to perform field and laboratory density tests, except that the Contractor shall make such additional tests, at his expense, as deemed necessary by him to assure that the work of compaction is performed properly, determine any adjustments in compacting equipment, thickness of layers, moisture content and compactive effort or other means necessary to obtain the specified minimum relative density. Provide access to the work and all men and machinery necessary to aid the testing laboratory personnel in performing field density tests or taking samples for laboratory tests. In general, tests and samples shall be made as the work proceeds.

B. The Owner shall have testing laboratory perform maximum density tests on materials to be compacted from samples submitted by Contractor taken from locations selected by the Engineer.

C. The Owner shall have testing laboratory perform field density tests of compacted backfill materials. The approximate location and number of such tests shall be as shown on the drawings, as described in the Bid Form, or as selected by the Engineer. Field density tests shall be taken as follows:

     1. In planted or unimproved areas:

          a. 18" above the top of the pipe

          b. Finished grade

     2. In streets, roads, parking lots or other paved areas:

          a. 18" above the top of the pipe

          b. 24" to 36" below the gravel road base

          c. Gravel road base subgrade

          d. Top of gravel road base

         e. Top of bituminous surface course

D. Copies of test results prepared by the testing laboratory shall be transmitted to the Contractor at the same time they are transmitted to the Engineer.

E. Successful performance of compaction at the location of the field density test shall not relieve the Contractor of his responsibility to meet the specified density requirements for the complete project.