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   PART 1 - GENERAL

    01 WORK INCLUDED

    A. Exterior excavation, backfilling of trenches and compaction required for the following utility service lines and/or equipment.

    1. Domestic/potable water.

    2. Sanitary waste/sewer and vent.

    3. Natural gas.

    1.02 JOB CONDITIONS

    A. Verify that survey benchmark and intended elevations for the Work are as indicated.

    B. Existing Utilities: Locate existing underground utilities in areas of work. If utilities are to remain in place, provide adequate means of support and protection during earthwork operations.

    C. Should uncharted, or incorrectly charted, piping or other utilities be encountered during excavation, consult utility owner immediately for directions. Cooperate with Owner and utility companies in keeping respective services and facilities in operation. Repair damaged utilities to satisfaction of utility owner.

    D. Do not interrupt existing utilities serving facilities occupied and used by Owner or others, during occupied hours, except when permitted in writing by Engineer/Contractor and then only after acceptable temporary utility services have been provided.

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

    1.03 USE OF EXPLOSIVES

    A. Do not bring explosives onto the site or use in work without prior written permission of Architect/Engineer and authorities having jurisdiction. Contractor is solely responsible for handling, storage, and use of explosive materials when their use is permitted.

    B. Protection of Persons and Property: Barricade open excavations occurring as part of this work and post with warning lights.

    C. Operate warning lights as recommended by authorities having jurisdiction.

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

    1.04 QUALITY ASSURANCE

    A. Refer to Specifications Section 15308: Plumbing General Provisions.

    B. Exterior plumbing piping systems, excavation, backfilling and compaction, trench shoring and any below listed associated items and methods shall meet with federal, state and local code requirements and guidelines.

   PART 2 - PRODUCTS

    02 MATERIALS AND INSTALLATION

    A. Refer to other sections of the specifications for specified types of utility piping and/or equipment.

   PART 3 - EXECUTION

    03 EXAMINATION

    A. Verify fill materials to be reused are acceptable.

    04 PREPARATION

    A. Identify required lines, levels, contours, and datum.

    B. Generally, compact subgrade to density requirements for subsequent backfill materials.

    C. Protect bench marks, existing structures, fences, sidewalks, paving, and curbs from excavation equipment and vehicular traffic.

    D. Protect existing above and below grade utilities which are to remain.

    05 EXCAVATION

    A. Underpin adjacent structures which may be damaged by excavation work, including utilities and pipe chases.

    B. Excavation cut shall not interfere with normal 45 degree bearing splay of foundation.

    C. Hand trim excavation. Remove loose matter.

    D. Remove lumped subsoil, boulders, and rock up to 1/3  cubic yards measured by volume.

    E. Notify Architect/Engineer of unexpected subsurface conditions and discontinue affected Work in area until notified to resume work.

    F. If unsuitable bearing materials are encountered at required subgrade elevations, carry excavations deeper and replace excavated material as directed by Architect/Engineer.

    G. Unauthorized excavation consists of removal of materials beyond indicated subgrade elevations or dimensions without specific direction of Architect/Engineer. Unauthorized excavation, as well as remedial work directed by Architect/Engineer, shall be at Contractor's expense.

    1. Under footings, foundation bases, or retaining walls, fill unauthorized excavation by extending indicated bottom elevation of footing or base to excavation bottom, without altering required top elevation. Lean concrete fill may be used to bring elevations to proper position, when acceptable to Architect/Engineer.

    2. Elsewhere, backfill and compact unauthorized excavations as specified for authorized excavations of same classification, unless otherwise directed by Architect/Engineer.

    H. Stability of Excavations: Slope sides of excavations to comply with federal, state and local codes and ordinances having jurisdiction. Shore and brace where sloping is not possible because of space restrictions or stability of material excavated.

    1. Maintain sides and slopes of excavations in safe condition until completion of backfilling.

    2. Shoring and Bracing: Provide materials for shoring and bracing, such as sheet piling, uprights, stringers and cross-braces, in good serviceable condition.

    3. Establish requirements for trench shoring and bracing to comply with local codes and authorities having jurisdiction.

    4. Maintain shoring and bracing in excavations regardless of time period excavations will be open. Carry down shoring and bracing as excavation progresses.

    5. Provide permanent steel sheet piling or pressure creosoted timber sheet piling wherever subsequent removal of sheet piling might permit lateral movement of soil under adjacent structures. Cut off tops as required and leave permanently in place.

    B. Dewatering: Prevent surface water and subsurface or ground water from flowing into excavations and from flooding project site and surrounding area.

    1. Do not allow water to accumulate in excavations. Remove water to prevent softening of subgrade foundation bottoms, undercutting footings, and soil changes detrimental to stability of subgrades and foundations. Provide and maintain pumps, well points, sumps, suction and discharge lines, and other dewatering system components necessary to convey water away from excavations.

    2. Establish and maintain temporary drainage ditches and other diversions outside excavation limits to convey rain water and water removed from excavations to collecting or run-off areas. Do not use trench excavations as temporary drainage ditches.

    C. Material Storage: Stockpile satisfactory excavated materials until required for backfill or fill. Place, grade and shape stockpiles for proper drainage.

    D. Locate and retain soil materials away from edge of excavations. Do not store within drip line of trees indicated to remain.

    E. Dispose of excess soil material and waste materials as directed by Architect/Engineer.

    F. Excavation for Trenches: Dig trenches to the uniform width required for particular item to be installed, sufficiently wide to provide ample working room. Provide 6 inches to 9 inches clearance on both sides of pipe or conduit.

    1. Excavate trenches to 6 inches below depth indicated or required and refill to proper grade with 3/4 inch washed gravel firmly compacted, or sand. Carry depth of trenches for piping to establish indicated flow lines and invert elevations. Beyond building perimeter, keep bottoms of trenches sufficiently below finish grade to avoid freeze-ups.

    2. Where rock is encountered, carry excavation 6 inches below required elevation and backfill with a 6 inch layer of crushed stone or gravel prior to installation of pipe.

    3. For pipes 5 inches or less in nominal size do not excavate beyond indicated depths. Hand excavate bottom cut to accurate elevations and support pipe or conduit on undistributed soil.

    4. For pipes 6 inches or larger in nominal size, tanks and other mechanical work indicated to receive subbase, excavate to subbase depth indicated or, if not otherwise indicated, to 6 inches below bottom of work to be supported.

    5. Grade bottoms of trenches as indicated, notching under pipe bells to provide solid bearing for entire body of pipe.

    3.02 BACKFILL AND FILL

    A. General: Place acceptable soil material in layers to required subgrade elevations, for each area classification listed below.

    1. In excavations, use satisfactory excavated or borrow material.

    2. Under grassed areas, use satisfactory excavated or borrow material.

    3. Under walks, steps and pavements, use satisfactory excavated or borrow material, or combination of both.

    4. Under building slabs, use drainage fill material.

    B. Backfill trenches with concrete where trench excavations pass within 18 inches of column or wall footings and which are carried below bottom of such footings, or which pass under wall footings. Place concrete to level of bottom of adjacent footing. Backfill trenches within structure and paved areas with crushed stone.

    1. Do not backfill trenches until tests and inspections have been made and backfilling authorized by Architect/Engineer. Use care in backfilling to avoid damage or displacement of pipe systems.

    C. Backfill excavations as promptly as work permits, but not until completion of the following:

    1. Acceptance of construction below finish grade.

    2. Inspection, testing, approval, and recording locations of underground utilities.

    3. Removal of concrete formwork.

    4. Removal of shoring and bracing, and backfilling of voids with satisfactory materials. Cut off temporary sheet piling driven below bottom of structures and leave in place.

    5. Removal of trash and debris.

    6. Permanent or temporary horizontal bracing is in place on horizontally supported walls.

    3.03 COMPACTION

    A. Backfill shall be thoroughly compacted with a heavy rammer or an approved mechanical tamper, or if the soil is of granular nature by puddling with hose and long pipe nozzle after the trench is backfilled, provided that under the location of pavement and other surfacing, the backfill shall be compacted solidly with mechanical tampers in layers not more than 6 inches thick, measured loose.

    B. Backfilling of trenches or other excavation shall be accomplished in a manner approved by the Architect/Engineer to insure in the opinion of the Architect/Engineer the following compaction:

    1. 95 percent compaction modified proctor within the building area.

    2. 90 percent compaction in parking area.

    C. Trenches for water lines shall be of a depth that shall provide a minimum cover over the top of the pipe of 3 feet below finished grade and avoid interferences of the lines with other utilities.

    D. Over depths shall be backfilled with loose, granular, moist earth, thoroughly tamped. Whenever wet, or otherwise unstable soil that is incapable of properly supporting the pipe is encountered in the bottom of the trench, such soil shall be removed to the depth required, and the trench backfilled to the proper grade with coarse sand, fine gravel or other suitable material.

    E. Piping shall not be installed in areas where fill for concrete floor is to be placed until after fill is placed. Fill shall then be replaced and compacted.

    3.04 DETAILS

    A. Refer to Contract Drawings for details.

    END OF SECTION