SECTION 312333 - TRENCHING AND BACKFILLING PART 1 - GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section. 1.2 SUMMARY A. Earth excavation and backfilling for construction of pipe and appurtenances, and for required removals. B. Disposal of excavated materials including stripping and stockpiling topsoil, salvage of material for backfill and removal of excess or material removed and not suitable for re-use. C. Excavation of surface materials, including pavements, drainage facilities, culvert pipes and end-walls. D. Maintenance of excavations including sheeting, dewatering, bridging, and fencing. E. Construction of bedding and pipe zone backfill. F. Construction of trench backfill. G. Construction of embankments. H. Excavation and backfill of test pits. I. Protection of utilities and maintenance in service of all utilities; including those to be removed; until said removal commences after replacement facilities have been constructed and placed in service. J. Compaction. K. Restoration of surfaces, including topsoil, drainage culverts, and ditches. L. Protection of trenches and open excavations. 1.3 RELATED SECTIONS A. Section 310000 Earthwork (Broadscope). B. Section 312501 Environmental Protection and Erosion and Sediment Control. C. Section 314100 Sheeting and Shoring. D. Section 315000 Structural Excavation, Backfill, and Compaction (Building Area). E. Section 331113.01 Ductile Iron Pipe. F. Section 333100 Sanitary Utility Sewerage Piping. 312333-1
G. Section 334104 Corrugated Polyethylene Storm Drain Pipe. 1.4 DEFINITIONS A. Earth Excavation: The removal of all material not classified as rock. B. Hand Trench Excavation: Excavations performed manually exceeding one cubic yard in any one operation. Hand trench excavation may be required to protect trees, utilities, etc. or as specified, shown on the Contract Drawings or as directed by the Architect/Engineer. C. Gravel Backfilling: The placement or replacement of all soil material as specified, shown on the Contract Drawings or as directed by the Architect/Engineer. 1.5 QUALITY ASSURANCE A. Allowable Tolerances: 1. Alignment of Excavation: To permit construction of pipe, structures, and appurtenances to the tolerances specified under pertinent drawings and specifications. a. Trench bottom vertical alignment: Do not excavate less, or 2 inches more at any point below proposed pipes and other structures than dimension shown on the Contract Drawings. b. Trench sides horizontal alignment: Do not excavate less than dimension shown on the Contract Drawings. c. Line of neat pavement cut: Do not vary more than 12 inches in 50 feet, and not more than one inch in 10 feet from a straight horizontal line. 2. Bedding: Construct bedding with specified material as indicated to produce the minimum levels relative to the pipe as shown on the Contract Drawings. B. Requirements of Regulatory Agencies: 1. Comply with New York State Department of Labor Board of Standards and Appeals Part 23 of Title 12. 2. Comply with Subpart P, "Excavations, Trenching, and Shoring" of U.S. Department of Labor OSHA Regulations for Construction. 3. Comply with rules, regulations, laws concerning construction activity in roads of the applicable jurisdiction: a. New York State Department of Transportation. b. County of Albany. c. Town of Guilderland. 4. Comply with all other applicable regulations. 1.6 SUBMITTALS A. Samples: 1. Before using material for special trench backfill, pipe zone backfill, or bedding, submit samples from each typical source to the Architect/Engineer for testing and approval as follows: 2. Submit two samples of material from each source used for trench backfill or bedding if other than on-site sand. 3. Submit two samples of crushed stone from each source, as shown in the Contract Drawings or Specifications, or ordered by the Architect/Engineer. 4. Submit two samples of Structural Fill used for trench backfill, as shown in the Contract Drawing or as ordered by the Architect/Engineer. 312333-2
1.7 DELIVERY, STORAGE, AND HANDLING A. Load and haul away excavated material not suitable for other uses at the site. Use haul routes approved by the municipality having jurisdiction. Use temporary dust control to keep haul routes clean and free of dust. Provide dump at Contractor's expense, and obtain approval for its use from municipality having jurisdiction. B. Store and stockpile material suitable for backfilling within rights-of-way and easements, away from interference with traffic, and nearby residents. Use all stockpiled material as soon as practical. Do not allow material to erode or wash into trench, onto road or adjacent property. 1.8 SITE CONDITIONS A. Sequencing, Scheduling: Notify the Architect/Engineer three working days in advance of the need for manhole and pipeline layout. B. Notify: Capital Area Underground Utilities Location Service (1-800-962-7962) 72 hours prior to starting excavation, for location of gas, telephone, and electric lines. C. Notify: Other private and public utilities in the work area. 1.9 GEOTECHNICAL ENGINEERING STUDY (SOILS REPORT) A. The Owner employed by C.T. Male Associates, P.C. (Geotechnical Engineer) to investigate sub-surface soil conditions and make recommendations regarding sitework construction procedures. Perform all work in accordance with the recommendations and requirements therein. If conflicts exist between the Geotechnical Evaluation and the Contract Drawings and Specifications, the more stringent requirements shall apply. PART 2 - PRODUCTS 2.1 MATERIALS A. Bedding: 1. On-Site Sand: Material shall be clean, as approved by the Architect/Engineer, and shall be practically free from silt, clay, organic matter, frozen sections, or other deleterious matter. It shall not contain slag, cinders, ashes, rubbish, or other foreign material. B. Pipe Zone Backfill: 1. On-Site Sand: Material shall be clean, as approved by the Architect/Engineer, and shall be practically free from silt, clay, organic matter, frozen sections, or other deleterious matter. It shall not contain slag, cinders, ashes, rubbish, or other foreign material. C. Special Trench Backfill: 1. Crushed Stone or Crushed Gravel: As specified in Section 703, Subsection 703_02 - Coarse Aggregate of the New York State Department of Transportation Standard Specifications for Construction and Materials, dated May 1, 2008 and all addenda thereto; and being of the specific size called for by the Architect/Engineer. 2. Run-of-Bank Gravel or Sand: 312333-3
a. Gravel shall be as specified in Section 667 Local Road Gravel Surface, Base, and Subbase Courses of the New York State Department of Transportation Standard Specifications for Construction and Materials, dated May 1, 2008 and all addenda thereto and being of the specific gradation called for; or a run of bank gravel of a gradation and from a source acceptable to the Architect/Engineer. b. Sand shall be as specified in Section 703, Subsection 703_01 - Fine Aggregate of the New York State Department of Transportation Standard Specifications for Construction and Materials, dated May 1, 2008 and all addenda thereto; or a run of bank sand acceptable to the Architect/Engineer. 3. Flowable Fill: As specified in paragraph 2.2.A of this section. D. Structural Fill: 1. Structural fill shall be as defined in the Geotechnical Evaluation. This material is an imported run-of-bank sand or sand and gravel which conforms to the limits of gradations listed below. Structural fill shall be used to backfill areas of utility removal. Imported Structural Fill Sieve Size Percent Finer by Weight 4-Inch 100 ¼ Inch 75 to 100 No. 40 50 to 95 No. 200 0 to 10 E. Embankment: 1. On-Site Sand: Material shall be clean, as approved by the Architect/Engineer, and shall be free of clay, organic matter, frozen material or other deleterious matter, including slag, cinders, ash or rubbish. 2. Structural Fill: As specified herein. 2.2 MIXES A. Flowable Fill: 1. Shall be a manufactured special trench backfill of the following proportions: a. Cement: 35 lb/cy. b. Aggregate (Sand and Gravel - 3/8 Maximum Size): 2,750 lb/cy. c. Water: 315 lb/cy. d. Air Entraining Agent: 20 lb/cy. 2. Shall be prepared by a ready mix supplier and delivered to the site premixed. 3. Shall be equal to the CLSM 0 Flowable Fill as manufactured by Clemente Latham Concrete Corp or equal. 4. Shall result in a backfill material which exceeds 95% relative optimum density upon installation. PART 3 - EXECUTION 3.1 INSPECTION A. Prior to all work, carefully inspect the site and verify that construction may properly commence. 312333-4
1. Before excavation verify: a. Work layout, horizontal and vertical, and conformance of layout with the Contract Drawings. b. Limits of construction. c. Surface drainage ditch and driveway culvert alignments, both vertical and horizontal. Also inspect culvert pipes and immediately report to the Architect/Engineer any condition which would prevent removal and reinstallation of culvert pipes to condition when found. d. Utility locations, including, but not limited to: aerial, pole-lines, buried, underground transmission, local service, and individual connections. e. Location, size and description of property to be replaced including, but not limited to: curbs, driveways, pavements, plantings, and lawn furnishings. f. Location of property markers, bench marks, USGS Monuments, settlement gauges, and ROW markers, within the Limits of Construction which may be moved by the Contractor's operations. 2. After excavation verify that pipe, structures, and appurtenances to be placed in trenches may be installed in accordance with pertinent drawings and specifications. 3. Before backfilling verify: a. Pipe, structures, and appurtenances have been installed in accordance with pertinent Contract Drawings and Specifications. b. Utilities are adequately continued, supported and maintained without damage. B. In the event of discrepancy or unsatisfactory condition, immediately notify the Architect/Engineer. 3.2 PREPARATION A. Notification: Before commencing excavation in any part of the job, notify the following: 1. The Architect/Engineer. 2. Adjacent and affected property occupants. 3. The Fire Department. 4. The Police Department. 5. All public and private utilities whose facilities are in the vicinity of the excavation. Notify UFPO 72 hours before excavating. B. Utility Protection and Changes: Where public and/or private utilities are encountered: 1. Maintain, support, and save from damage all public utilities. 2. Allow reasonable time and space for owners of private utilities to cooperate in maintaining their facilities. 3. Excavate test pits: a. As required by the Contract Drawings or as directed by the Architect/Engineer. b. In advance of construction to determine precise location of obstructions, utilities. C. Site Clearing and Surface Removal: Prior to excavation of trench: 1. Clear the work area. 2. Strip topsoil and stockpile for re-application. 3.3 PERFORMANCE A. Excavation: Perform all earth excavation for construction of pipe, appurtenances, structures, bedding, and backfill. Remove surface materials and drainage facilities: 1. Disposal of excavated material: a. Store material suitable for backfill. Protect from contamination. 312333-5
b. All surplus earth, rock and other unsuitable or unsatisfactory material shall be transported and placed on spoil areas specified in the Contract Drawings at the elevations and grades shown. If spoil areas are not shown, all spoil and surplus materials shall be disposed of at an off-site location approved by the Architect/Engineer. c. The Contractor shall furnish written approval from the owner of the spoil disposal site for such disposal. 2. Remove pavement to neat straight lines for pavement restoration when excavating through pavement to remain. Remove pavement to allow for a minimum of 6 inches of undisturbed base on each side of trench for pavement replacement. 3. Perform excavation in such manner and to such widths as will give ample room for installing the pipe, appurtenances and structures, and for sheeting, bracing, pumping, and draining. 4. Do not disturb bottom of excavation at structures requiring a cast-in-place concrete base. In case material is disturbed, carefully excavate to undisturbed level and fill with concrete at no additional cost to the Owner. 5. Unauthorized Excavation: Unauthorized excavations carried outside lines and grades shown on Contract Drawings shall be filled by Contractor at no additional cost to the Owner as follows: a. Below concrete cradle, concrete encasement or concrete foundation, fill unauthorized excavations with 3,000 psi concrete. b. Below specified bedding, fill unauthorized excavations with compacted bedding material. 6. Maintenance of Trench: a. Keep sides of excavation from slides, cave-ins. Use any method including, but not limited to: b. temporary sheeting, shoring, bracing, cribbing. c. Furnish and install sheeting and shoring to support the sides of all trenches and other excavations. Remove sheeting and shoring as excavation is filled up, except where the Architect/Engineer orders the sheeting left in place. d. Keep excavations free from water. Use any method including but not limited to gravity flow, pumping, sumps. Maintain excavation in a dry condition until backfill has been placed and compacted a minimum of 18 inches above top of pipe. In all cases, maintain dry trench at backfill level. 7. Schedule: a. Advance excavation operations ahead of pipe-laying to allow for circumstances such as rock, other utilities. b. Limit excavations ahead of pipe-laying a maximum of 200 feet, unless more is approved by the Architect/Engineer in writing. c. Confine excavation operations to reasonable limits to facilitate traffic movement and reduce inconvenience to property of the Owner. B. Bedding and Pipe Zone Backfill: 1. The trenches for pipelines shall have bottoms as shown on the Contract Drawings conforming to the required grades. All excavations for pipelines shall be made to the depths shown for pipe bedding. 2. If the bottom of trench becomes unsuitable for pipe laying, due to Contractor's operations, he shall provide extra excavation and backfill suitable to the conditions at the area and bedding specified, at no additional cost to the Owner. 3. If the bottom of the trench is soft and, in the opinion of the Architect/Engineer, cannot support the pipe or structure, additional trench depth shall be excavated as ordered by the Architect/Engineer, and refilled with specified crushed stone. 4. On-Site Sand: a. Inasmuch as the pipe will be bedded in on-site sand no excavation will be required below the bottom of the pipe other than shaping the existing material to receive the pipe bells or joints. Prior to the said shaping, a plate tamper shall be utilized to compact the subgrade of the pipe to 95% Modified Proctor Density. 312333-6
b. The placement and compaction of bedding material shall continue in 6-inch thick loose lifts on each side of the pipe up to the spring line of the pipe. Each loose lift shall be hand compacted to 95% Modified Proctor Density. c. Place Pipe Zone Backfill material in 6-inch thick loose lifts on each side of the pipe up to plane 12-inches above the top of the pipe. Hand compact each layer to 95% Modified Proctor Density. 5. Class A Concrete Cradle Bedding (If ordered by the Architect/Engineer): a. Place and compact 3,000 psi concrete in trench bottom. b. Settle the bottom of pipe into fresh concrete at correct line and grade. c. After construction of pipe, place and compact 3,000 psi concrete each side of the pipe as shown on the Drawings. d. Place Pipe Zone Backfill material in 6-inch thick loose lifts on each side of the pipe up to a plane 12 inches above the top of the pipe. Hand compact each layer to 95% Modified Proctor Density. 6. Class A Concrete Encasement (If ordered by the Architect/Engineer): a. Same requirements as for Concrete Cradle, except increase the concrete to cover the pipe a minimum of 6 inches and exclude the Pipe Zone Backfill, as shown on the Drawings. b. Place a layer of 15 lb. asphalt impregnated felt on the concrete before backfilling. 7. Bedding Compaction: a. Below pipe and structures: Compact to not less than 95% of Modified Proctor maximum density, at or below optimum moisture content in conformance with ASTM D 1557. b. Material shall be deposited evenly on both sides of the pipe in tamped layers not exceeding 6 inches in depth until at least three-fourths the depth of the pipe has been reached. For wide trenches tamping shall be done for a distance on each side of the pipe equal to at least the diameter of pipe. Any pipe that is damaged or moved out of alignment, regardless of cause, shall be replaced or realigned at the Contractor's expense. 8. Ditch Line Dikes: 9. Construct an impervious earth dike at trench bottom to keep free water from traveling downstream along pipe and eroding pipe bedding. a. Construct dike of clay or other impervious material. b. Construct one foot thick and from bottom of trench to top of pipe and at every manhole, and other places as directed by the Architect/Engineer. C. Trench Backfill: 1. Trench backfill shall be on-site sand or Structural Fill as specified, shown on the Drawings, or as directed by the Architect/Engineer. Material shall be placed and compacted as follows: a. Within 18-inches of subgrade elevation, on-site sand backfill shall be placed in 12-inch thick loose lifts and mechanically compacted to 95% Modified Proctor maximum density. b. Up to within 18-inches of subgrade elevation, on-site sand backfill shall be placed in 15- inch thick loose lifts and mechanically compacted to 95% Modified Proctor maximum density. c. Do not backfill against masonry walls or other structures until they have attained sufficient strength to safely resist the thrust of fill materials. d. Do not backfill with frozen materials. e. If settlement or washout occurs before Final Inspection, furnish, place, and compact additional material to resurface the low places as directed by the Architect/Engineer. f. Maintain dust control at all times. 2. Heavy equipment shall not be allowed to pass over the pipe until a fill of at least 2 foot depth has been placed over the pipe. In any case, movement of construction equipment and all other vehicles and loads over and adjacent to any pipe shall be done at the Contractor's risk. When determined by the Architect/Engineer, any pipe that is damaged or disturbed through any cause shall be replaced as directed by the Architect/Engineer, at the expense of the Contractor and at no cost to the Owner. 3. Methods of Compaction: 312333-7
a. Hand Compaction: b. Tamping by hand with flat hand tampers. c. Mechanical Compaction: d. Compaction by means of vibratory or other mechanical tampers. 4. Backfilling and consolidation shall be by one of the following procedures, as directed by the Architect/Engineer, depending on the nature of the backfill material and the location of the trench. a. Cross-country conditions and lawns where reasonable subsequent trench settlement can be tolerated: 1) Backfill material shall be placed in 2-foot layers compacted to 90% Modified Proctor. The top layer shall be similarly compacted and mounded as required to allow for subsequent settlement. The surface shall be maintained prior to fine grading and seeding, and thereafter repaired as necessary for the duration of the maintenance period. D. Special Trench Backfill: 1. Crushed Stone or Crushed Gravel: Shall generally be required in extremely wet trench conditions primarily for Pipe Zone Backfill. 2. Run-of-Bank Gravel or Sand: Shall be required under highways and other paved areas as Pipe Zone Backfill and/or Special Trench Backfill when excavated material is unsatisfactory as directed by the Architect/Engineer: a. Trench backfill material in trench excavations ranging from 0 to 10 feet deep, measured from invert of pipe to finished grade, in non-paved areas as designated by the Architect/Engineer shall be placed and compacted in accordance with paragraph 3.3.C.4.a.1) herein. b. Trench excavations exceeding 10 feet deep over the invert of the pipe shall be placed and compacted in accordance with paragraph 3.3.C.4.b.1) herein. 3. Flowable Fill: Shall generally be required in County and State highway rights-of-way whenever paved areas are excavated by the open cut method. Flowable fill shall be used as directed by the Architect/Engineer. E. Test Pits: 1. Excavate test pits for location of utilities which may affect the location of proposed work, at times and locations as shown on the Contract Drawings, or as directed by the Architect/Engineer. 2. Size: 3 feet x 6 feet to the depth required, unless larger pit is ordered by the Architect/Engineer. 3. Prior to excavation, notify the Architect/Engineer, and affected utility owners. 4. Test pits shall include excavation, temporary sheeting, dewatering, backfill and temporary pavement. F. Utility Protection: 1. Support and protect from injury all existing utility lines and structures which are encountered, uncovered or hazarded by excavation operations, which do not, in the opinion of the Architect/Engineer, require to be changed in locations. If damaged or removed, restore to as good condition as when found at Contractor's expense. 2. Provide temporary channels of flow for all water courses, and restore to original condition at completion of backfilling. 3. Give written notice to owners of existing utilities or structures in time for them to cooperate in protecting their property. 4. Contractor shall hold the Architect/Engineer harmless against: a. Obstructions to flow of drains, ditches, or streams. b. Injury to electric, telephone lines, gas, and water lines. G. Maintenance of Utilities: 312333-8
1. During the construction of this project all utilities shall be maintained in service except as necessary to construct the building. The portion of the existing Sanitary Sewer to be removed and properly disposed of shall be maintained in service until replacement facilities are connected and can themselves be placed in service. Replacement facilities shall be connected and the existing structures to which they connect can be modified without interruptions in service. Where the sewer line and appurtenances have been removed, excavations shall be backfilled with Structural Fill. H. Restoration of Surfaces: 1. After backfilling, restore surfaces and facilities to as good condition or better than they were found. 2. On paved surfaces disturbed by digging, place and compact subbase granular material to match the original pavement elevation immediately after backfilling is completed. 3. Immediately after backfilling, restore all other surfaces and facilities as follows: a. Where possible, mound additional fill or topsoil over trench line to provide for settlement. b. Replace drainage culverts and pipes, end sections, and walls, removed for excavation to their original position. Provide granular bedding and backfill suitable for each installation. Shape, trim and compact surface to receive pavement or surface treatment of similar or like kind and quality as that which was removed. c. Shape, trim and compact ditches, water courses, swales to original cross-section and profile. Place topsoil, seed and maintain until intended vegetation has been reestablished. Where water velocities produce a scouring or erosion in ditches, provide jute mesh or riprap to stabilize as directed by the Architect/Engineer. d. Grade, trim, compact lawns and open areas. Spread topsoil on disturbed areas and seed. Furnish make-up topsoil if sufficient material has not been adequately stockpiled. I. Maintenance of Roadways and Sidewalks: 1. Conduct construction operations so as to leave open and free passage at sidewalks, cross walks, and carriageways. 2. Maintain hydrants, fire/police alarm boxes, mail boxes, accessible for use. 3. Provide temporary bridge(s) of adequate design and construction where open trench crosses walkways, roadways, or driveways. a. Provide hand railing for bridges used for walks. b. Maintain temporary bridges in a safe, neat condition, suitably lighted at night. J. Temporary Wire Fence: 1. Where trenches and open excavations are left unattended during non-working hours or days, furnish and maintain temporary for: a. Excavations having sides steeper than one vertical to one horizontal. b. Excavations deeper than 5 feet. 2. A temporary wire fence shall not be required where temporary sheeting is extended a minimum of 3 feet above ground surface, and no void exists between sheeting and side of excavation. Provide signs in accordance with 4.a and 5.b below. 3. Provisions for this fencing are in addition to provisions the Contractor would normally make to safeguard his work operations and in no way diminish his obligations in this respect. 4. Materials: a. Signs: "DANGER - KEEP OUT" message. Size: b. 16" x 24". 5" black letters on orange background. c. Posts: Steel angle, wood or barricades, suitable to provide adequate support. 5. Construction Details: a. Construct temporary fence to completely surround all excavations as required. b. Mount "DANGER - KEEP OUT" signs at intervals not exceeding 50 feet along fence line. 312333-9
c. Provide posts or adequate supports for fencing at intervals not in excess of 10 feet. Stretch and fasten wire fabric at top, middle, and bottom of each support. END OF SECTION 312333 312333-10