8-23 Provide the class of concrete indicated in the plan s.
Obtain approval if field conditions necessitate a variance from the plan dimensions of the structure and footings. Construct endwalls on the end of a full joint of pipe and in accordance with the details in the plans. Any endwall that incorporates an opening for circular pipe 54 inches or greater shall be reinforced.
C.Backfill Complete endwall construction, a nd remove all forms. Backfill with approved material after the concrete or brick masonry has cured for at least 7 curing days unless otherwise permitted. A “ curing day” is defined in Article 830 -5. Within 4 calendar days after the completion of the 7 day curing period, shape, compact and complete backfill in accordance with the contract.
838-4 Measurement and Payment
Endwalls will be measured and paid in cubic yards of concre te or brick completed and accepted. This quantity will be computed from the dimensions shown in the plan s or from revised authorized dimensions. Where precast concrete units have been approved and are used instead of cast-in-place units the quantity to b e paid will be computed the same as if cast-in-place units were used, as no reduction in pay quantity will be made due to the use of precast instead of cast-in-place endwalls. Reinforced Endwalls will be measured and paid in cubic yards of concrete or bri ck completed and accepted. This quantity will be computed from the dimensions shown in the plan s or from revised authorized dimensions. Where precast concrete units have been approved and are used instead of cast-in-place units the quantity to be paid will be computed the same as if cast -in- place units were used, as no reduction in pay quantity will be made due to the use of precast instead of reinforced cast -in-place endwalls. Payment will be made under: Pay Item Pay Unit Endwalls Cubic Yard Reinforced Endwalls Cubic Yard
840-1 Description
Perform the work covered by this section including, but not limited to , excavation; providing protection of employees in excavation; hauling; disposal of materials; removing existing pipe and drainage structures at the site of the work; furnishing, transporting and placing foundation conditioning material, backfill material, subsurface drainage, concrete, brick masonry, block masonry, precast units, mortar, grout, reinforcing steel, hardware, castings and miscellaneous metal; fabrication; welding; and galvanizing to construct cast- in-place concrete, brick m asonry, block masonry or precast concrete inlets, catch basins, junction boxes, spring boxes, manholes, concrete aprons and other minor drainage structures excluding endwalls, with all necessary metal grates, covers, frames, steps and other hardware, in ac cordance with the contract. Use cast -in place concrete, brick masonry, block masonry or precast concrete construction as shown on approved plans.
8-24 840-2 Materials
Refer to Divis ion 10. Item Section Brick 1040 -1 Concrete Block 1040 -2 Curing Material s 1026 Fabricated Steel Grates 1074 -9 Gray Iron Castings 1074 -7 Joint Filler 1028 -1 Joint Sealers 1028 -2, 1028 -3 Mortar 1040 -9 Precast Drainage Structure Units 1077 Portland Cement Concrete, Class B 1000 Reinforcing Steel 1070 Select Materials 1016 Steps 1074 -8 Structural Steel 1072 Use grout in precast structures consisting of one part Portland cement to two parts of mortar sand. Use foundation conditioning material meeting Article 1016 -3 for Class V or VI select material as shown in the contract or as directed.
840-3 Construction Methods
A.Excavation Perform excavation with equipment of adequate weight, size and capability. Where necessary, provide a competent person and protection of personnel in excavation by sloping, shoring or bracing in accordance with Federal , State or local standards and Article 11 107-1.
B.Foundation Do not place masonry drainage structure until the foundation has achieved adequate strength. Where the foundation material is found to be of poor supporting value or of rock, minor adjustments in the location of the structure may be approved to provide a more suitable foundation. Where this is not practical, undercut the foundation and condition by backfilling with an approved select material. Set precast structure foundations to within ± 1/2 inch of grade on a 2 inch to 3 inch thick bed of compacted foundation conditioning material.
C.Cast -In-Place Concrete, Brick and Block Masonry Install drainage structures to plan line and grade or approved to meet drainage conditions. Do not modify the drainage structure by corbel ing or use of concrete slabs unless otherwise directed by the Engineer . Construct concrete in accordance with Section 825 and give an ordinary surface finish. Construct brick masonry in accordance with Section 830. Construct block masonry in accordance w ith Section 834. Furnish and place reinforcing steel in accordance with Section 425. Obtain approval if field conditions necessitate a variance from the plan d imensions of the structure or footings.
8-25 (D) Installation of Precast Units
Install drainage structure s to plan line and grade or approved to meet drainage conditions. Do not modify the drainage structure by corbeling or use of concrete slabs unless otherwise directed by the Engineer . Assemble the precast drainage structure units in accordance with the manufacturer's instructions. Subarticle 840 -3(C) applies where it is necessary to use cast -in-place concrete, brick masonry or block masonry construction as part of the structure. Fill any void greater than 1 inch with a brick or block bat fully encased in mortar . Obtain approval if field conditions necessitate a variance from the plan dimensions of the structure or footings.
E.Fittings and Connections As the work is built up, accurately space, align and thoroughly b ond fittings that enter the structure. Make pipe connections so the pipe does not project beyond the inside wall of the drainage structure and grout as necessary to make smooth and uniform surfaces on the inside of the structure. Set metal frames for grates and covers in full mortar beds or secure by approved methods.
F.Backfill Complete drainage structure and remove all forms and falsework. Backfill with approved material, compacted to the density required by Subarticle 235- 3(C), after the drainage structur e has cured for at least 7 curing days, unless otherwise permitted. Define a “curing day” in accordance with Article 825 -9 for concrete or Article 830- 5 for brick or block masonry.
G.Pipe Collars and Pipe Plugs Construct pipe collars and pipe plugs in accor dance with the details shown in the plans or as directed by the Engineer . Use any class of Portland cement concrete contained within Section 1000 for pipe collars. Construct pipe plugs with either brick masonry or any class of Portland cement concrete contained within Section 1000.
H.Concrete Aprons Construct concrete aprons in accordance with the details in the plans. Use Class B or higher compressive strength concrete.
840-4 Measurement and Payment
Masonry Drainage Structure that incorporate an opening for circular pipe not exceeding 48 inches in diameter will be measured and paid in unit s of each for the actual numb er completed and accepted. Masonry Drainage Structure exceeding a height of 5.0 f eet will be measured and paid in linear feet for the portion of the drainage structure exceeding a height of 5.0 f eet. The height will be measured vertically to the nearest 0.1 f eet from the top of the bottom slab to the top of the wall. For that portion of Masonry Drainage Structure measured above a height of 10.0 f eet, payment will be made at 1.3 tim es the contract unit price per linear foot for Masonry Drainage Structure . Masonry Drainage Structures that incorporate an opening for circular pipe exceeding 48 inches in diameter, or for pipe arch of any size, will be measured and paid on a volume basis as provided below.
8-26 Masonry to be paid will be the number of cubic yards of cast -in-place concrete brick or block
that has been incorporated into the completed and accepted structure. This quantity will be computed from the dimensions shown in the plan s or from revised dimensions authorized by the Engineer. Where the wall thickness is greater than the wall thickness shown in the plan s due to the use of oversize brick or for any other reason, the wall thickness shown in the plans will be used to compute qua ntities except where an increase in wall thickness has been authorized by the Engineer. Pipe Collars will be measured and paid in cubic yards of concrete or brick that has been incorporated into the completed work. The cubic yards of pipe collars will be computed from the dimensions shown in the plan s or from revised dimensions authorized by the Engineer. Pipe Plugs will be measured and paid in cubic yards of concrete or brick that has been incorporated into the completed and accepted pipe plug. The cubic yards of pipe plugs will be computed from the dimensions shown in the plan s or from revised dimensions authorized by the Engineer. Frame with Grate and Hood, Std. _ ___ will be measured and paid in units of each for actual number of assemblies incorporated into the completed work. No separate measurement will be made of grates, hoods, and covers that are part of the assembly, as the grates, hoods and covers will be considered to be part of the c omplete assembly. Frame with Grate, Std. ____ will be measured and paid in units of each for actual number of assemblies incorporated into the completed work. No separate measurement will be made of grates, hoods, and covers that are part of the assembly, as the grates, hoods and covers will be considered to be part of the complete assembly. Frame with Two Grates, Std. ___ _ will be measured and paid in units of each for actual number of assemblies incorporated into the completed work. No separate measurem ent will be made of grates, hoods, and covers that are part of the assembly, as the grates, hoods and covers will be considered to be part of the complete assembly. Frame with Cover, Std. ___ _ will be measured and paid in units of each for actual number of assemblies incorporated into the completed work. No separate measurement will be made of grates, hoods, and covers that are part of the assembly, as the grates, hoods and covers will be considered to be part of the complete assembly. Steel Frame with Two Grates, Std. ____ will be measured and paid in units of each for the actual number of fabricated steel grates incorporated into the completed work. No separate payment will be made for c oncrete aprons shown in Roadway Standard Drawings No. 840.17, 840.18, 840.19, 840.26, 840.27 and 840.28, as this work will be incidental to the other work in this section. Foundation Conditioning Material, Minor Structures will be paid as provided in Article 300- 9. The above prices and payments will be full compensation for all work covered by this section.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 363–366 of 857.