421 Page 290421 BOX, PIPE, AND PLATE PIPE CULVERT UNDERCUTTING
421.1DESCRIPTION
This work consists of the removal of unstable material and rock, either in ledge or boulder formation, below the bedding grade of box, pipe, and plate pipe culverts, and the backfilling of undercut areas.
421.2MATERIALS
A.Backfill Material: Material for backfilling the undercut areas of pipe and plate pipe culverts will consist of stable material free of organic matter and rock. When specified in the plans or as required by the Engineer the backfill material will conform to that used for backfilling undercut areas of box culverts. If backfill material conforming to that used for backfilling undercut areas of box culverts is not included in the plans but is required by the Engineer, the Engineer will process a CCO to provide for compensation to the Contractor for the added cost of the changed material. Material for backfilling the undercut areas of box culverts will conform to the following: Sieve % Passing 1 1/2 inch 100 1 inch 95 - 100 #4 0 - 75 #200 0 - 18.0 If undercut depth exceeds 3 feet below the bottom of the structure and stable material is not encountered, oversized rock material may be used up to the bottom of the undercut limits shown on the plans. B.Bedding Material: Bedding material for precast concrete box culverts and granular bedding material when required for pipe culvers will be sand or selected sandy soil conforming to the following: Sieve % Passing 3/8 inch 100 #200 0 - 10.0 C.Extruded Insulation Board (Polystyrene): Extruded insulation board (polystyrene) will conform to AASHTO M230.
421.3CONSTRUCTION REQUIREMENTS
A.General: If the Engineer determines field conditions warrant change, the plan limits of the undercutting may be increased, decreased, or eliminated. The width of undercutting for pipe culverts will be the outside diameter of the pipe plus 4 feet or the outside span of arch pipe plus 4 feet. If the undercut material is disposed of, the disposal will be at locations acceptable to the Engineer. 421 Page 291Backfill will be compacted in accordance with Section 120.3 B.3.a , specified density method. Backfill will be compacted to 95% or greater of the maximum dry density in horizontal layers not to exceed 6 inches loose depth. If the backfill material does not contain enough fines to allow for conventional density testing (SD 105 or SD 106), the material will be compacted in the manner described in firm, unyielding surface satisfactory to the Engineer. B.Box Culvert: Undercut dimensions will be to the minimum dimensions shown on the plans, unless otherwise directed by the Engineer. C.Pipe Culvert : A moisture/density test is required in the foundation soil under all rural mainline cross pipes prior to installation. The foundation soil density will be in accordance with the specified density method. The foundation soil will be improved by one of the following methods, as directed by the Engineer. 1.Scarifying the foundation soil to a depth of 6 to 8 inches and recompacting. 2.Undercutting the foundation soil and replacing or recompacting. Under this item of work, the removal of unstable material, ledge rock, and boulder formation rock below the bedding grade of pipe culverts and the backfilling of undercut areas will be performed. Pipe culverts placed on embankment soil (in the fill and not on natural ground) will not require pre- installation testing of the foundation soil provided that the fill area has been included in normal embankment testing zones. The Engineer may order undercutting of pipe not included in the plans. D.Extruded Insulation Board (Polystyrene): No equipment will be allowed on the uncovered insulation board. The backfill covering the insulation board will be spread and compacted in such a manner that the equipment used will be operated on a minimum of 6 inches of backfill material at all times.
421.4METHOD OF MEASUREMENT
limit will be the bedding grade of the box culvert. The dimensions and lower limits will be as specified on the plans unless otherwise directed by the Engineer. B.Pipe and Plate Pipe Culvert Undercut: Undercutting pipe and plate pipe culverts will be measured by the cubic yard. The upper limit will be the lower face of the pipe, except the upper limit for pipe culverts to be installed on a Class B bedding will be 1 foot below the lower face of the pipe. The width, length, and lower limits will be as specified. C.Extruded Insulation Board (Polystyrene): Extruded insulation board (polystyrene) will be measured to the nearest square yard. 421 Page 292421.5 BASIS OF PAYMENT A.Box Culvert Undercut: This work will be paid for at the contract unit price per cubic yard, under the item box culvert undercut. The basis of payment will be for plans quantities unless additional undercutting is directed by the Engineer. When additional undercutting is required, the adjusted quantity of undercutting will be paid for at the contract unit price regardless of the backfill material used. Payment will be full compensation for equipment, labor, tools and incidentals required for undercutting and for furnishing, placing, watering and compacting backfill material, including bedding material when specified on the plans. B.Pipe and Plate Pipe Culvert Undercut: This work will be paid for at the contract unit price per cubic yard, under the item pipe culvert undercut. All costs for undercutting pipe culverts including equipment, labor, tools, and materials for furnishing, placing, watering, and compacting backfill in place of excavated material will be incidental to the contract unit price for pipe culvert undercut. The quantities listed in the table of pipe culvert undercut are based on the undercut width specified above, and a depth of 1 foot for all pipes 36 inches in diameter and greater. When undercutting culverts is required at other locations or to a different depth than specified, the adjusted quantity of undercutting will be paid for at the contract unit price. Undercutting pipe and plate pipe culverts will be paid for at the rate specified in Section 4.4. All costs for scarifying the foundation soil including equipment, labor, watering, and compacting the scarified soil will be incidental to the contract unit price per foot for pipe culvert installation. C.Extruded Insulation Board (Polystyrene): Extruded insulation board (polystyrene) will be paid for at the contract unit price per square yard. Payment will be full compensation for labor, equipment, and incidentals to furnish and install the extruded insulation board (polystyrene). 422 Page 293422 DRAINAGE FABRIC PROTECTION FOR CAST IN PLACE REINFORCED CONCRETE BOX CULVERTS
422.1DESCRIPTION
This work consists of placement of drainage fabric protection around the outside of all cast in place reinforced concrete box culvert joints.
422.2MATERIALS
Drainage Fabric: Drainage Fabric will conform to Section 831, Type A.
422.3CONSTRUCTION REQUIREMENTS
Drainage fabric will be placed entirely around each joint in the box culvert barrel. The fabric will be placed to provide a minimum of 2 1/2 feet of fabric centered on the joint. Where required, transverse joints in the fabric will be overlapped a minimum of 2 feet. During bottom slab construction the fabric will be placed prior to concrete placement. Sufficient adhesive will be required along the edges of the fabric to hold it in place during backfilling.
422.4METHOD OF MEASUREMENT
Separate measurement will not be made.
422.5BASIS OF PAYMENT
Separate payment will not be made. The cost of providing drainage fabric will be incidental to other contract items.