CATEGORY 400 STRUCTURES SECTION 482 — INVERT OF PAVING STRUCTURES
482.01 Description
Furnish and install a paved reinforced grout invert to various structures and fill undermined or eroded areas of a structure with grout. Seal leaks and joints in pipes, concrete slabs, or box culverts with grout or other materials as specified. When specified, furnish and coat the exposed metal of the pipe with a coal tar epoxy.
482.02 Materials
Reinforcement Steel 908.01, Uncoated Epoxy Bonding Compound 921.04 Carbon Steel Anchor Fasteners (Hardware) 909.10 Water 921.01 Curing Materials 902.07 Coal Tar Epoxy 483.02
482.02.01 Grout. Grout shall consist of 846 lb/yd3 of Type II Portland cement, mortar, sand
aggregate, 6 + 1 percent air entrainment by volume, and water proportioned to provide a pumpable mixture. The 28 day compressive strength shall be a minimum of 3500 psi. Ready mixed high strength grout may be permitted with permission of the Engineer. Ensure that the ready mixed high strength grout is furnished by a manufacturer approved by the Administration and as specified in Section 915.
482.02.02 Sealing leaks. Provide a non-toxic, VOC compliant, rapid expansive, hydrophobic, closed
cell, polyurethane resin that cures through exposure to the air. The project data sheet can also call the material a polyurethane grout or polyurethane foam. The resin should have a fast reaction time, be rapid setting, and not wash away from the spray of water. Ensure that any material used is NSF 61 (National Sanitation Foundation) certified to encounter drinking water. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS The material shall conform to the following requirements: TEST PROPERTY TEST METHOD SPECIFICATION LIMITS Uncured Specific Gravity D 792 1.01 - 1.30 Shrinkage at -20° F D 2126 0% Viscosity D 4889 50 – 400 cps Cured Density – Free Rise D 1622 1.5 – 2.5 pcf If multiple products exist that meet this description, ensure that the correct material is used at the appropriate location at no additional cost to the Administration.
482.03 Construction
Provide adequate temporary lighting and proper ventilation for the confined spaces as specified in TC-3.04.
482.03.01 Maintenance of Stream Flow. Install all sediment and erosion control and maintenance
of stream flow devices, like dewatering devices, stream diversion dikes, and stream diversion pumps and hoses in accordance with the Plans and permits prior to doing any of the paved invert repairs. Maintenance of stream flow shall be continuous as specified in 308.03.42. Secondary inflows such as median inlets, manholes, etc. may be blocked off allowing ponding in areas that do not negatively affect roadways, properties, features, etc. as determined by the Engineer. Alternatively, the secondary inflows may be pumped or directed to nearby, storm drains, or either end of the pipe being paved. All controls for secondary inflows must be approved by the Engineer prior to installation. Invert paving of these structures may be performed in stages when approved. Install all sediment and erosion control devices to dewater each staged area and maintain stream flow including those from secondary inflows. At the start and end of each stage, adjust the controls as needed for the subsequent stage.
482.03.02 Invert Cleaning. Remove and dispose of all debris at the inlet, outlet, and inside the pipe
by hand or by water blast cleaning. Refer to 303.03.07. If the invert of the pipe has been an existing bituminous invert, remove it using chipping hammers. The Contractor is alerted that the quantity of debris varies based on erosion and deposition. Bids shall account for anticipated changes in debris. No additional compensation will be given for changes in the debris quantities from those assumed at the time of bidding. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS Provide smooth transitions at the inlet and outlet to gradually slope the grade from the cleaned elevation to the original ground within the limits of disturbance as shown in the Contract Documents. If excavation outside the limits of the structure is needed, complete it as Class 5 Excavation as specified in Section 202. Prior to sealing leaks and paving the structure invert, water blast clean all surfaces of the existing structure that will be in contact with the new grout invert including any surface areas with protective coatings. When cleaning the surfaces of existing structure, use a minimum pressure of 4,000 psi measured at the nozzle, and a rotary tip. Collect all wash water from the cleaning operation in approved dewatering devices, filters, and basins. No wash water may enter the stream without passing through these devices.
482.03.03 Sealing Leaks. Immediately after cleaning, inspect the structure with the Engineer to
locate any water leaks along the length of the invert. Sealing leaks will be required if the volume of water leaking into the structure meets the following criteria:
a.A steady flow of water collects in the invert of concrete structures or corrugations of metal structures, and
b.results in a continuous flow or stream through the dewatered structure. Seal the areas with holes, missing sections of structure, or joint locations where water is leaking into the structure with an approved polyurethane resin. Follow the manufacturer’s recommendation to seal the leaks and fill all voids under the structure around a leak. These sealed areas shall prevent any water from entering the structure and conform to the shape of the structure. If the structure contains corrugations, do not fill in the bottom corrugations. In this case, remove any sealant above the top surface of the bottom corrugation, “trough area.” Ensure that the grout paving can occupy the same area in a sealed location as it does in an area that is not sealed. Sealing leaks will not be required if the Engineer determines that leaks are insignificant and should have no adverse impact to installation of the grout invert. When needed, use sump pits dug into the invert of the pipe with dewatering pumps at intervals and locations directed by the Engineer to draw down excess water leaking into the pipe. Fill these holes with grout once they are no longer needed.
482.03.04 Reinforcement Steel. Install all reinforcing steel including any anchors, as specified.
Ensure that welding is as specified in 430.03.19 and 430.03.20. The requirements for radiographic and ultrasonic inspection may be waived if a visual inspection by the Engineer indicates the welds are satisfactory for the purpose intended. When field welding, use the shielded metal-arc process. Where reinforcing steel is to be welded to a corrugated pipe that has a galvanized surface, remove the galvanized coating with power tool prior to welding.
482.03.05 Grout placement. Ensure that the surface of the structure to be paved is free of all loose
scale, concrete, rust; oil, asphalt coatings, or any other foreign material that could act as a bond breaker. Ensure that the surface is clean and dry prior to placing the grout. Mixers and agitators as specified in 915.03.05. The concrete/grout pump shall be capable of delivering up to 25 yd 3/hr. Invert paving may be completed using either pumping or pouring. Pneumatically applied mortar is prohibited. Maintain the same slope on the paved invert as the existing structure and obtain a smooth broom finished surface regardless of method used. Provide a bulkhead at all construction joints to create a vertical surface. Coat the entire face of any construction joint with an approved epoxy bonding compound. Ensure all reinforcement is continuous through the construction joints. Cure the paved invert using methods specified in 420.03.09(b), 420.03.09(c), 420.03.09(d), or
420.03.09 (f). Do not permit the stream water to flow over the grout surface for a minimum of
36 hours after completing the last grout placement.
482.03.06 Coal Tar Epoxy Coat. When specified inside a metal pipe, apply a coal tar epoxy coating
to all exposed metal after grout invert is placed as specified in Section 483. In lieu of what is specified in 483.03.01, clean all surfaces as specified in 436.03.10(a), 436.03.10(b), and 436.03.10(g). Perform spot cleaning in areas of heavy corrosion as specified in 436.03.10(f). If the existing structure already has a coal tar epoxy coating, the Engineer may only require cleaning and coating areas of coating failure and corrosion, in lieu of cleaning and coating the entire structure. In this instance, clean and repair only the areas directed by the Engineer as specified above. To promote good adhesion of the new coating, lightly abrade and feather the edges of the existing coating within two inches of new coatings application. In areas where the contractor removed the existing protective coating beyond the limits shown on the plans and is not covered by the new grout invert or coal tar epoxy, repair the original coating as specified by the Engineer. Ensure that the coal tar epoxy coating overlaps the grout invert by at least 4 inches. 482.03.07 Clean up. At the completion of all repairs in the waterway, remove dewatering devices, stream diversion dikes, and stream diversion pumps and hoses without spillage of the collected materials. Return the construction area to preconstruction conditions or better. This may require the use of stabilization matting, seeding, and mulch as directed by the Engineer and specified in Sections 704, 705, and 709. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS
482.04 Measurement and Payment
2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS The payment will be full compensation for all material, labor, equipment, tools, and incidentals necessary to complete the work.
482.04.01 Invert Paving will be measured and paid for at the Contract unit price per square yard. The
payment will be full compensation for ventilation of confined spaces, temporary lighting, digging and filling sump holes, grinding or cutting repair areas, furnishing, installing, and welding reinforcing steel and anchors, installing and removing forms, and furnishing, placing, and curing of grout for invert paving.
482.04.02 Clearing and grubbing will be measured and paid for as specified in 101.04.
482.04.03 Maintenance of stream flow including the installation, maintenance, and removal of all
stream diversion devices, pumps, generators, and dewatering equipment will be paid for as specified in 308.04.62.
482.04.04 Excavation of materials beyond the limits of the structure will be measured and paid as
class 5 excavation as specified in 202.04. 482.04.05 Cleaning and removing material and debris inside the structure including removal of existing invert material will be measured and paid for as specified in 303.04.16. Payment will include water blast cleaning and collection and disposal of runoff.
482.04.06 Sealing joints between structure sections and other leaks will be measured and paid for at
the Contract unit price per gallon for the pertinent Polyurethane Resin for Sealing Leaks item. Payment will include the initial and all subsequent inspections of the structure for leaks. No payment will be made if the resin applied area continues to leak any water after the material has cured. This is a contingent item just to establish a unit cost for the polyurethane resin and GP-4.04 will not apply to this item.
482.04.07 Furnishing and applying the coal tar epoxy coating will be measured and paid for at the
Contract unit price per square foot for the pertinent Cleaning and Coating item. Payment will include cleaning the exposed metal surfaces and preparing all other surfaces.
482.04.08 Repairing an existing coal tar epoxy coating will be measured and paid for at the Contract
unit price per square foot for the pertinent Cleaning and Repairing Existing Coating item. Payment will include cleaning the exposed metal surfaces, preparing all other surfaces, and furnishing and applying all necessary coating materials.
482.04.09 Temporary seed and mulch will be measured and paid for as specified in 704.04.
482.04.10 Permanent seed will be measured and paid for as specified in 705.04.
482.04.11 Soil and slope stabilization matting will be measured and paid for as specified in 709.04.
483 — COAL TAR EPOXY COATING CATEGORY 400 STRUCTURES SECTION 483 — COAL TAR EPOXY COATING
483.01 Description
Furnish and apply a protective coal tar epoxy coating system to the existing steel in the areas specified in the Contract Documents.
483.02 Materials
The coal tar epoxy coating shall be a VOC compliant, self-curing two component system consisting of resin and the catalyst and shall meet the Corps of Engineers Formula C-200 or SSPC-Paint No. 16. The material shall be processed and packaged in a manner that ensures within a period of one year from date of manufacture, that it will not gel, liver or thicken deleteriously, or form gas in the closed container. Coatings and vehicles shall be packaged in standard containers not larger than 5 gal with removable friction or lug type covers. Each container of separately packaged component shall be clearly and durably labeled to indicate the purchaser’s order number, date of manufacture, manufacturer’s batch number, quantity, color, component identification, material safety data sheet (MSDS), and the designated name and formula or specification number of the coating together with special instructions.
483.03 Construction
Refer to Section 436 - Cleaning and Painting Structural Steel.
483.03.01 Surface Preparation. Clean all surfaces to be coated as specified in 436.03.10(a),
436.03 10(b), and 436.03.10(h) except clean surfaces within 6 in. of the mean low waterline to
bare metal having a minimum surface profile height of 1 mil. Ensure that all surfaces to be coated are completely dry, free of moisture, soil, dust, grit, etc., at the time the coating is applied. Remove any traces of oil, grease, or other organic matter prior to coating by using solvent, spot blasting, or as directed by the Engineer. Any additional surface preparation, temperature and humidity ranges, and application methods shall be as recommended by the manufacturer and approved by the Engineer.
483.03.02 Mixing. Perform all mixing in accordance with the manufacturer’s specifications and
by use of mechanical mixers. Only full containers of components A and B packaged by the manufacturer shall be used for mixing, as measuring portions for smaller or larger batches is 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS
Source: Maryland Standard Specifications for Construction and Materials, 2025 Edition. Pages 607–611 of 1,113.