3-1 Division 3
PIPE CULVERTS
300-1 General
Excavate, undercut, provide material, condition foundation, lay pipe, joint and couple pipe sections and furnish and place all backfill material as necessary to install the various types of pipe culverts and fittings required to complete the project. Install pipe in accordance with the detail s in the plans. Do not waste excavation unless permitte d. Use suitable excavated material as backfill; or in the formation of embankments, subgrades and shoulders; or as otherwise directed by the Engineer . Furnish disposal areas for the unsuitable material. The Engineer will identify excavated materials that are unsuitable. Where traffic is to be maintained, install pipe in sections so half the roadway width is available to traffic.
300-2 Material S
Refer to Division 10. Item Section Flowable Fill, Excavatable 1000 -7 Grout, Type 2 1003 Geotextiles , Type 4 a 1056 Joint Materials 1032 -6(F) Select Materials 1016 Provide foundation conditioning material in accordance with Article 1016 -3 for Class V or VI select material as shown in the contract. Provide bedding material in accordance with Article 1016 -3 for Class II (Type 1 only) or Class III select material as shown in contract. Provide backfill material in accordance with Article 1016 -3 for Class II (Typ e 1 for flexible pipe) or Class III select material as shown in the contract. Provide filtr ation geotextile in accordance with Section 1056 for any type of geotextile . Provide foundation conditioning geotextile and geotextile to wrap pipe joints in accordance with Article 1056 for Type 4a geotextile . Do not use corrugated steel pipe in counties listed in Article 310 -2.
300-3 Unloading and Handling
Unload and handle pipe with reasonable care. Do not roll or drag metal pipe or plates over gravel or rock during handling. Take necessary precautions to ensure the method used in lifting or placing the pipe does not induce stress fatigue in the pipe. Use a lifting device that uniformly distributes the weight of the pipe along its axis or circumference. Repair minor damage to pipe when permitted. R emove pipe from the project that is severely damaged or is rejected as being unfit for use. Undamaged portions of a joint or section may be used where partial lengths are required.
3-2 300-4 Preparation of Pipe Foundation
Prepare the pipe foundation in accordance with the applicable method as shown in the contract, true to line and grade and uniformly firm. Where material is found to be of poor supporting value or of rock and when the Engineer cannot make adjustment in the location of the pipe, undercut existing foundation material within the limits established i n the plans. Backfill the undercut with foundation conditioning material . Encapsulate the foundation conditioning material with foundation conditioning geotextile before placing bedding material. Overlap all transverse and longitudinal joints in the geotextile at least 18 inches . Maintain the pipe f oundation in a dry condition.
300-5 Invert Elevations
The proposed pipe culvert invert elevations shown on the Drainage Summary Sheets are based upon information available when the plans were prepared. If proposed invert elevations are adjusted during construction based upon actual conditions encountered, no claim for an extension of time for any reason resulting from thi s information will be allowed. When a pipe culvert is to be installed in a trench and the average actual elevation of the pipe between drainage structures deviates from the average proposed elevation shown on the Drainage Summary Sheets by more than one foot , a pay adjus tment will be made as follows: Pay Adjustm ent (per linear foot) = ( )[ ]( ) CUP AAE APE × ± −15 . 0 Where: APE = Average Plan Elev. = ( )
2.. Elev Outlet Plan Elev Inlet Plan + AAE = Average Actual Elev. = ( )
2.. Elev Outlet Actual Elev Inlet Actual + CUP = Culvert Pipeof riceP Unit Contract When the actual location of a pipe culvert is changed from the location shown i n the plans, the Engineer will make a pay adjustment deemed warranted based upon the relation of the pipe culvert as shown in the plans to the finished roadway and the relation of the pipe culvert as constructed to the finished roadway. The top elevation column on the drainage summary sheet indicates the flow elevation at the top of structures intended to collect surface water. The top elevation column on drainage structures not intended to collect surface water indicates the elevation at the top of the cover.
300-6 Laying Pipe
The Department reserves the right to perform forensic testing on any installed pipe.
A.Rigid Pipe Concrete and welded steel pipe will be considered rigid pipe. Lay pipe on prepared foundation, bell or groove end upgrade with the spigot or tongue fully inserted. Check each joint for alignment and grade as the work proceeds. Use flexible joint material except when material of another type is specified in the contract. Joint material of another type may be used when permitted.
3-3 Repair lift holes in concrete pipe, if present. Thoroughly clean and soak the lift hole and
complete ly fill the void with grout. Submit alternate details for repairing lift holes to the Engineer for review and approval. For all pipes 42 inches in diameter and larger, wrap geotextile around all pipe joints. Extend geotextile at least 12 inches beyond ea ch side of the joint. Secure geotextile against the outside of the pipe by methods approved by the Engineer.
B.Flexible Pipe Corrugated steel, corrugated aluminum, polypropylene , HDPE and PVC pipe will be considered flexible pipe. Place flexible pipe caref ully on the prepared foundation starting at the downstream end with the inside circumferential laps pointing downstream and with the longitudinal laps at the side or quarter points. Handle coated corrugated steel pipe with special care to avoid damage to coatings. Join corrugated steel and corrugated aluminum pipe sections with coupling band, fully bolted and properly sealed. Provide coupling bands for annular and helical corrugated metal pipe with circumferential and longitudinal strength sufficient to preserve the alignment, prevent separation of the sections and prevent backfill infiltration. Match - mark all pipe 60 inches or larger in diameter at the plant for proper installation on the project. Only a t locations with rod and lug connect ors indicated in the plans, join corrugated steel pipe sections together with rod and lug coupling bands, fully bolted. Use sleeve gaskets in conjunction with rod and lug couplings and seal the joints properly. For HDPE, polypropylene, and PVC pipe use a gasketed bell and spigot connection where not otherwise specified in the plans. Only a t locations w ith coupl ers indicated in the plans, join HDPE and polypropylene pipe sections together with coupling bands. Provide c oupling bands with circumferential and longitudinal strength sufficient to preserve the alignment, prevent separation of the sections and prevent infiltration of backfill material.
300-7 Backfilling
Loosely place bedding material, in a uniform layer, a depth equal to the inside diameter of the pipe divided by 6 or 6 inches , whichever is greater. Leave bedding material directly beneath the pipe uncompacted and allow pipe seating and backfill to accomplish compacti on. Excavate recesses to receive the bells where bells and spigot type pipe is used. Place fill around the pipe in accordance with the applicable method shown i n the plans in layers not to exceed 6 inches loose unless otherwise permitted by the Engineer . Compact to the density required by Subarticle 235 -3(C). Approval of the backfill material is required before its use. Use select material as shown in the contract. Take care during backfill and compaction operations to maintain alignment and prevent damage to the joints. Keep backfill free from stones, frozen lumps, chunks of highly plastic clay or other objectionable material. Grade and maintain all pipe backfill areas in such a condition that erosion or saturation will not damage the pipe foundation or backfill. Flowable fill may be used for backfill when approved by the Engineer. When using flowable fill, ensure that the pipe is not displaced and does not float during backfill. Submit methods for supporting the pipe and material placement to the Engineer for review and approval. Do not operate heavy equipment over any pipe until it has been properly backfilled with a t least 3 feet of cover. Place, maintain and finally remove the required cover that is above the
3-4 proposed finished grade . Remove and replace pipe that becomes misaligned, shows excessive
settlement or has been otherwise damaged by the Contractor's operations.
300-8 Inspection and Maintenance
Ensure proper jointing and that deformations do not exceed allowable limits as described in the Department’s Guidelines for Post Installation Evaluation and Repair of Newly -Installed Drainage Pipe . Maintain all pipe installations in a condition such that they wi ll function continuously from the time the pipe is installed until the project is accepted by the Engineer . The Engineer will randomly video, deflection test, and/or manually inspect installations of completed pipelines prior to final acceptance.
300-9 Measurement and Payment
No measurement will be made of any work covered by this section except as listed below. Removal and disposal of existing pavement and unsuitable material above the pipe invert are a part of the excavation for the new pipe culvert installation. Repair of the pavement will be made in accordance with Section 654. Placing, maintaining and removing the required cover is incidental to the work of this section. Removing and replacing pipe that becomes misaligned, shows excessive settlement or has been otherwise damaged by the Contractor's operations is incidental to the work of this section.
A.Using Local Material Undercut Excavation is all excavation removed by undercutting below the bottom of the trench as staked. Undercut Excavation will be measured as the actual number of cubic yards of undercut excavation, measured in its original position and computed by the average end area method, that has been removed as called for in the contract and will be paid at double the contract unit price for Unclassified Excavation in accordance with
Article 225 — 7.
Local material used for conditioning the foundation will be measured and paid in accordance with Article 225-7 for Unclassified Excavation or in accordance with
Article 230 — 5 for Borrow Excavation depending on the source of the material.
Local material used to replace pipe undercut excavation will be measured and paid in accordance with Article 225-7 or Article 230-5.
B.Using Other than Local Material No measurement and payment will be made for Undercut Excavation. The material used to replace pipe undercut excavation will be classified as foundation conditioning material. Foundation Conditioning Material, Minor Structures will be measured and paid as the actual number of tons of this material weighed in trucks on certified platform scales or other certified weighing devices . No direct payment will be paid for Undercut Excavation . Payment at the contract unit price for Foundation Conditioning Material, Minor Structures will be full compensation for all work of pipe undercut excavation.
C.Foundation Conditioning Geotextile Foundation Conditioning Geotextile will be measured and paid in square yards. The measurement will be based on the theoretical calculation using length of pipe installed and two times the standard trench width. No separate measurement will be made for overlapping geotextile or the vertical geotextile dimensions r equired to encapsulate the foundation conditioning material.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 127–130 of 857.