840-1 DESCRIPTION
When it is necessary that drawings be furnished by the Contractor for approval, the Engineer, upon receipt, shall forward them to the
Plans
and Standards Management for review and approval along with any recommendations and comments he deems appropriate.
840-2 MATERIALS
Producers are allowed to stockpile standard precast items. This allows for faster completion of construction projects and allows for better response time for Department Technicians in inspecting these completed items. The
Materials & Tests Unit will handle inspection and testing of the material. Once the items have been tested and accepted, each piece will have an NCDOT RFID Barcode Tag and may be stamped “NCDOT APPROVED.” The “NCDOT APPROVED” stamp is not required and the tag should be used as the means for accepting the structure. Shipping of material that has not been approved may result in the producer being removed from the Department’s Precast Concrete Quality Control/Quality Assurance Program and the
producer will not be allowed to produce material for stock. Once an item has been tagged/stamped approved, it shall be stored in an area designated for Department approved materials. A test report will be generated by the Materials & Tests Technician and filed in the Records Section of the Materials & Tests Unit.
When the item is delivered to a project, the project personnel will verify that the item is approved for use by ensuring that it is
tagged and the structure is “Authorized” and “Available” in the M&T Precast database. Each item cast must have the RFID Barcode tag attached to the unit. Additional markings such as company logos are optional.
A
Materials Received Report will be completed. The tag should be scanned with the M&T provided scanner or manually record the number in order for the unit to be received and entered into HiCams for acceptance. Ensure that all information such as sizes, piece numbers, and name of manufacturer are listed on the Materials Received Report. Prior to installation, the project personnel will inspect the items for any damage which may have occurred during shipment such as cracks, breaks, etc., and reject any items they find unacceptable. A test report for the item will not be sent to the Engineer. However, the Field Inspection Report is available in
HiCAMS.
840-3 CONSTRUCTION METHODS
(A) EXCAVATION
All
OSHA requirements and other regulations governing trenching and shoring shall be observed. If the Technician observes a condition that constitutes “imminent danger” he should immediately direct the Contractor to cease the offending operation and immediately contact the Engineer.
The order to cease can be hand written with a copy retained for project records.
(B) FOUNDATION
The Technician shall check and approve the foundation prior to the placement of any masonry by the Contractor. If the foundation material is of poor supporting value, the existing material may be undercut and backfilled as directed by the Engineer. If the Technician is unsure of the adequacy of the supporting value of the foundation material, he shall consult with the Engineer. The backfill material should be compacted to a degree comparable to the undisturbed adjacent material. In precast installations, a foundation conditioning material is required in order to stabilize the bottom slab and evenly distribute the loads to the foundation.
(C) CAST-IN-PLACE CONCRETE, BRICK, AND BLOCK MASONRY
The Engineer has the authority to vary the dimensions of the structure and footings to fit field conditions. Appropriate entries shall be made in the pay record books stating the reasons for the variance in these dimensions and indicating clearly the shape, size, etc., of the structure.
(D) INSTALLATION OF PRECAST UNITS
The precast unit components should be examined carefully for any structural damage during shipment and handling of the components. The Engineer, if necessary, may authorize minor repairs. The manufacturer's recommendations should be followed during assembly of the unit. A structurally sound and functioning drainage unit must be the end result of the installation. When assembling precast drainage structure units seal joints with a flexible butyl rubber. Major repairs to the units should not be undertaken without prior consultation with the
Materials & Tests Unit.
Pipes cannot be installed in the corners of precast masonry drainage structures unless a hole has been cast specifically for that purpose. The only portion of a precast drainage structure that can be removed for pipe installation is the three-inch knock-out. No horizontal or vertical members can be removed.
Following installation of a precast masonry drainage structure, the drainage structure invert must be filled with an approved concrete up to the elevation of the outlet pipe. The bottom of the drainage structure should be cleaned of any soil or debris before the invert is poured.
(E) FITTINGS AND CONNECTIONS
All pipe shall be cut flush with the inside wall and grouted as necessary to provide a smooth and uniform surface on the inside of the structure. Pipe should be cut prior to building the surrounding wall. The use of
non-shrink grout is recommended. The grout shall be cured. Approved non-shrink grouts are listed on the following website:
All metal frames shall be set in full, mortared beds or otherwise secured by methods approved by the Engineer.
(F) BACKFILL
Backfilling shall not be done until the structure has been cured for at least seven curing days unless otherwise permitted by the Engineer. The Technician shall check the degree of compaction of backfill adjacent to the structure. Inadequate backfill compaction adjacent to miscellaneous drainage structures is a source of maintenance problems. Periodic density tests shall be run on this backfill. When a density test is not performed, the Technician shall check by probing, etc., to determine if the backfill material is thoroughly compacted throughout its depth. Preferably, the Technician should be present to observe the complete backfill operation. The Technician should check the drainage structure after its completion and before final acceptance of the project to determine if any settlement has occurred. If settlement is observed, the Contractor should properly correct the situation.
ADDITIONAL CONCERNS
Masonry drainage structures that are within four feet of a travel way must be traffic bearing unless they are in
2’-6” curb and gutter or in a concrete traffic island. If drainage structures are installed in expressway gutter or shoulder berm gutter and are within four feet of the travelway they must be traffic bearing. For these types of installations, a precast solid wall structure is considered traffic bearing.
The Technician should verify that the correct grates and frames are used.
Traffic phasing may require that a traffic bearing drainage structure/grate and frame be used where a non-traffic bearing drainage structure/grate and frame are required by the plans for the final traffic pattern.
840-4 MEASUREMENT AND PAYMENT
The Technician should document all pipes entering the box so that they may be deducted from the quantities of the drainage structure in the pay record book.
Payment for foundation conditioning material utilized under minor precast drainage structure floor slabs will be made in accordance with
Article 300-9.
ADDITIONAL RESOURCES
