CONSTRUCTION SPECIFICATION FOR EXCAVATING AND BACKFILLING - STRUCTURES

Transcription

1 ONTARIO PROVINCIAL STANDARD SPECIFICATION METRIC OPSS 902 DECEMBER 1983 CONSTRUCTION SPECIFICATION FOR EXCAVATING AND BACKFILLING - STRUCTURES SCOPE REFERENCES DEFINITIONS TABLE OF CONTENTS SUBMISSION AND DESIGN REQUIREMENTS Cases Requiring Submission.02 Number of Drawings.03 Submission Requirements MATERIALS Clay Seal.02 Granular.03 Backfill Not Used CONSTRUCTION Protection Schemes.02 Excavation Excavation for Foundations.02 Excavation for Backfill and Frost Tapers.03 Approval of Excavation.04 Preservation of Channel.05 Disposal and Use of Excavate Materials Unwatering Structure Excavation Backfilling General.02 Clay Seal Not Used Page 1 Rev. Date: 12/1983 OPSS 902

2 MEASUREMENT FOR PAYMENT Structures.02 Granular Backfill BASIS OF PAYMENT Excavation and Backfill.02 Unwatering Structure Excavation(s).03 Granular Backfill to Structure.04 Clay Seal.05 Overexcavation SCOPE This specification covers the requirements for excavating, for unwatering and for the protection of roadway, railway and other works when excavating is carried out in their vicinity REFERENCES This specification refers to the following standards, specifications or publications: Ontario Provincial Standard Specifications, Construction: OPSS 206 OPSS 501 OPSS 502 OPSS 539 Construction Specification for Grading Compacting Weighing of Materials Protection Schemes Ontario Provincial Standard Specifications, Material: OPSS 1010 OPSS 1205 Aggregates, Granular A, B, C, D and 16 mm Crushed Types A and B Clay Seal DEFINITIONS For the purpose of this specification the following definitions apply: Bedding: means granular material to be placed in areas so designated on the contract drawings. Bridge: means a structure which carries highway pedestrian and/or railway traffic but not including culverts or tunnels unless so designated on the drawings. Channel: means a natural or artificial water course. Culvert: means a structure which is designated as a culvert in the contract documents and which is designed to provide an opening under a roadway, pedestrian way, railway or side entrance for the passage of surface water, livestock or pedestrians. Designated Payment Surface: means the original ground surface shown on the drawings unless specially designated surface is shown. Where a specially designated payment surface is shown, it will be indicated either by elevation, or by profile which is horizontal in the transverse direction at any point on it. Page 2 Rev. Date: 12/1983 OPSS 902

3 For rock excavation the designated payment surface will be the existing rock surface as established in the field before rock excavation unless a specially designated surface is shown. Earth: means soil. For payment purpose earth shall include all soils and any other material to be excavated not classified as rock, except concrete and stone masonry. Foundation: means that portion of the ground below the structure base, or footings which support the structure or that portion of the ground below the pile caps. Granular: means material meeting the requirements of OPSS Rock: means natural beds or massive fragments of the hard, stable cemented parts of the earth's crust (igneous, metamorphic or sedimentary in origin, may or may not be weathered), includes boulders having a volume of 1 m or greater. Soil: means all loose or moderately cohesive organic or inorganic deposits of the earth's crust such as silt, sand, gravel or clay or any of their mixtures. Structure: means any bridge, concrete culvert, retaining wall, dock, guideway, building or sign support SUBMISSION AND DESIGN REQUIREMENTS Cases Requiring Submission The Contractor shall provide working drawings for protection schemes in the following cases: 1. Where the contract requires the submission of working drawings, showing protection schemes for roadway, railway, waterway, structure excavation or other works liable to be impaired by the excavation or a temporary slope. 2. Where alternative scheme to the one shown on the contract is proposed. 3. Where details of the protection schemes are not shown in the contract. 4. When requested. The Contractor shall provide working drawings for unwatering schemes when requested Number of Drawings The drawings shall be submitted to the Engineer in the following numbers: Roadway protection, river protection and protection to excavation, such as cofferdams, sheeting, sheet piling or the like. 6 copies Protection where another Authority is affected, such as in work on a railway or navigable waterway. 3 additional copies per Authority Page 3 Rev. Date: 12/1983 OPSS 902

4 Submission Requirements Working drawings for protection schemes shall be submitted for approval a minimum of six weeks before carrying out the work where other authorities are involved and a minimum of three weeks in all other cases. Proposals submitted by the Contractor shall bear the seal and signature of a Professional Engineer who is a member of or is licensed by the Association of Professional Engineers of Ontario. Work affected by the protection schemes shall not proceed until the working drawings have been approved in writing by the Engineer. Design of such temporary works shall conform to the requirements of OPSS 539. Where unwatering is involved structural requirements of the scheme shall conform to the above. The unwatering requirements of the scheme shall be submitted a minimum of two weeks before carrying out the work MATERIALS Clay Seal Where clay seal is issued it shall comply with the requirements of OPSS Granular Granular material designated to be used for backfill and frost tapers shall meet the requirements of OPSS Backfill Material used for backfill shall be of quality and type acceptable to the Engineer and free from large or frozen lumps, wood, sod and other organic extraneous material CONSTRUCTION Protection Schemes The construction of all protection schemes shall conform to the requirements of OPSS 539. Where the stability, safety or function of an existing roadway, railway or other works can be impaired by an excavation or temporary slope, the Contractor shall provide such protection as may be required, including sheeting, shoring, and the driving of piles where necessary, to prevent damage from such works. Unless otherwise specific in the contract documents or unless otherwise authorized by the Engineer, materials used for protection shall remain the property of the Contractor and shall be removed from the right of way Excavation Excavation for Foundations All rock or other hard foundations shall have all loose or soft material removed to present a clean firm surface. Page 4 Rev. Date: 12/1983 OPSS 902

5 When a footing is to rest on an excavated surface other than rock, special care shall be taken not to disturb the bottom of the excavation. In soft conditions, the final removal of material to foundation level shall not be made until the Contractor is ready to proceed with the construction of the footing. In the case of concrete culverts of the open footing type, no excavation shall be made between the footings below the level streambed or the top of the footings whichever elevation is lower, unless authorized by the Engineer. The elevation of the bottom of the footing may only be changed with the approval of the Engineer who will consider matters such as design and economy in obtaining satisfactory foundation. Overexcavation shall be replaced by a material suitable for the particular application and on the approval of the Engineer. This material shall be compacted to the density required by OPSS 501 where materials other than concrete have been used. When shown on the plans, or when in the opinion of the Engineer, or when conditions warrant it, the Contractor shall carry out such addition excavations as may be required to construct concrete working slabs or granular pads or in the case of culverts of the box type, to permit the placing of granular bedding material Excavation for Backfill and Frost Tapers Excavation for backfill and frost tapers shall be to the neat lines shown on the contract drawings. Overexcavation shall be replaced material approved by the Engineer. The material shall be compacted to the density required by OPSS Approval of Excavation After each excavation is completed, the Contractor shall notify the Engineer and no footing, backfill or frost taper backfill shall be placed until the Engineer has approved the excavation and the character of the foundation material Preservation of Channel The Contractor shall ensure that the channel is brought back to its original condition unless otherwise specified in the contract Disposal and Use of Excavate Materials The Contractor shall use all suitable excavated material for the fill requirement of the contract. Disposal of excavated material which is unsuitable for, or which is surplus to, the requirements of the contract shall be disposed of, either within or outside the contract limits as set out elsewhere in the contract. Disposal or stockpile areas outside the contract limits shall be provided by the Contractor. Disposal or stockpile areas within the contract limits will be indicate in the contract Unwatering Structure Excavation The Contractor shall carry out all work to prevent disturbance to the foundation and, unless otherwise specified in the contract, he shall place the concrete in the dry. Unless otherwise specified in the contract, all temporary unwatering and support structures shall remain the property of the Contractor and shall be removed from the right-of-way when they are no longer required. Page 5 Rev. Date: 12/1983 OPSS 902

6 Backfilling General Open excavation surrounding footings shall be backfilled to the top of the footings with acceptable earth, as soon as the concrete has set. No fill shall be placed against an abutment, wingwall, retaining wall or concrete culvert until permission has been obtained from the Engineer and not until the concrete has reached 70 percent of its design strength. Filling around culverts, arches, rigid frames and piers shall proceed simultaneously and evenly on both sides so as to avoid any differential of the surface elevation of the fill material in excess of 0.6 m. When the Contractor has been authorized to proceed with the general backfilling, all spaces excavated and not occupied by abutments, piers or other permanent work shall be backfilled to the level of the surrounding ground or to the required grade whichever is the lower. Where concrete culverts are to be covered by rock embankments, the culvert shall be protected against damage. No traffic or construction equipment shall be permitted to pass over the culvert until the minimum cover has been placed in accordance with the contract. Granular material shall be placed within the lines and grades shown on the plans. All backfill shall be compacted according to OPSS Clay Seal When clay seal is shown on the contract drawings the Contractor shall place the clay seal to the dimensions shown MEASUREMENT FOR PAYMENT Structures "Earth Excavation for Structure" and "Rock Excavation for Structure" shall apply to the specific structure(s) designated, i.e. Bridge, Retaining Wall or Concrete Culvert and shall be measured in cubic metres. The quantity of excavation for each structure shall include only the quantities as measured below the designated payment surface within the limits shown in the contract. The quantity of excavation for each structure shall also include, where applicable, the quantities as measured below the designated payment surface for placing granular backfill and for placing the granular frost tapers to the theoretical lines shown on the drawings. For open footing culverts the quantity of excavation shall also include the quantities measured below the designated payment surface but between the plan areas of the footings and above the streambed or the tops of the footings whichever is higher. Where the structure excavation overlaps excavation required for other work the measurement shall be made as specified with no deduction for overlaps. Page 6 Rev. Date: 12/1983 OPSS 902

7 The volume of boulders in an excavation shall be determined on the basis of the three maximum rectilinear dimensions. Where boulders, classified as rock, are to be measured for payment the following provisions shall apply: 1. Only the amount removed shall be considered for payment. 2. The volume of the boulders removed shall be deducted from the volume of excavation as calculated above. The measurement of the total volume of materials considered for payment shall not exceed the calculated volume of excavation within the theoretical lines Granular Backfill The quantity of granular backfill and granular bedding shall include only those quantities measured below the subgrade and as measured within the theoretical line and grades shown on the drawings. Where the Contractor has excavated beyond the limits shown on the drawings the following conversion basis shall be used in measurement of the excess volume when it is replaced with granular: 1 m 3 weighs 2.0 t The weighing of granular material shall conform with the requirements of OPSS BASIS OF PAYMENT Excavation and Backfill Payment at the contract price(s) fro the tender item(s) "Earth Excavation for Structure" and "Rock Excavation for Structure" shall be full compensation for labour, equipment and material for all excavation required, protection of the excavation, protection of adjacent works, unwatering, backfilling and compacting around the footing according to sub-section , placing and compacting of suitable material in fill in accordance with OPSS 206 and disposal of any surplus or unsuitable excavated material, including the cost of disposal areas, all according to the requirements of this specification. When the Engineer requests excavation for concrete working slabs, granular working pads or granular bedding, payment shall be at the contract price for the appropriate excavation item Unwatering Structure Excavation(s) Payment at the contract price for the tender Item(s) "Unwatering Structure Excavation(s)" shall be full compensation for all labour, equipment and material to do the work according to the specifications as set out in the contract Granular Backfill to Structure Payment at the contract price for the appropriate granular tender item shall be for compensation for all labour, equipment and material involved in the placing of the backfill and granular bedding to the structure, the granular material for the fr tapers, the material at weep hole drains, for compacting the material and all other work required to place and ensure compaction of material, all according to the specifications and the requirements of the contract. Page 7 Rev. Date: 12/1983 OPSS 902

8 Clay Seal Payment at the contract price for the tender item "Clay Seal" shall be full compensation for all labour, equipment and material to place and trim the clay seal as required by the contract Overexcavation Payment will not be made for overexcavation due either to the Contractor's method of operation or his negligence, nor for the treatment of such overexcavation as explained in clauses and.02. Page 8 Rev. Date: 12/1983 OPSS 902