CATEGORY 300 DRAINAGE SECTION 305 — MISCELLANEOUS STRUCTURES
305.01 Description
Construct miscellaneous cast in place concrete or masonry drainage structures, furnish and install precast concrete drainage structures, and clean existing drainage structures including but not limited to inlets, manholes, junction boxes and risers. Apply integral color admixture to concrete structures when specified. Apply sandblast finish to the completed, colored drainage structures.
305.02 Materials
No. 57 Aggregate 901.01 Mortar Sand 901.01 Curing Compound 902.07.03 Portland Cement Concrete 902.10, Mix No. 2, 3, or 6 Grout 902.11 Brick 903.02 Mortar 903.06 Reinforcement Steel Section 908 Steel 909.02 Castings for Frames, Covers, Gratings and Steps 909.04 Zinc Coating A153 Precast Concrete End Walls, Inlets, and Manholes M 199
305.03 Construction
Refer to Section 420 for Portland cement concrete, Section 463 for brick masonry, and 402.03.01 for excavated material.
305.03.01 Construction Sequence. Complete the underground drainage structures before
placing the roadway surfacing. Manholes, catch basins, and inlets shall not be completed to final grade until the grading has been finished and all necessary arrangements have been made to ensure suitable connections and tie ins at proper grade and alignment with pavements, gutters, and curbs. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS
305.03.02 Castings. Set frames for grates and covers for inlets and manholes, in full beds of
mortar and rigidly secure them in place to the specified grade and alignment.
305.03.03 Pipe Connections. Set or cut inlet and outlet pipes flush with the inside face of the
structure. Extend them a sufficient distance beyond the outside face of these walls to provide for making proper connections. Completely and neatly close the joint around the pipe in the structure wall with mortar or other specified materials.
305.03.04 Inverts. When drainage structures contain two or more pipes, construct channeled
inverts conforming to the Contract Documents. 305.03.05 Drainage Structures. Provide two blockouts, each at least 8 in. diameter, in inlets and manholes for underdrains. Backfill with No. 57 aggregate for a width of 1.5 ft outside of the structure and extended from the bottom of the structure to the subgrade.
305.03.06 Precast Drainage Structures. For structures not detailed in the Contract Documents,
submit working drawings for approval. Certification. Certification from the manufacturer is required for each shipment of precast units. Provide a copy of the certification to the Engineer, the Laboratory, and the Contractor with each shipment. One copy shall remain at the plant. Include the name and address of the manufacturer, the type of structure, the identification number, the date of manufacture, the date of shipment, a statement indicating conformance with the Specifications, and the signature of the quality control manager. Mark the unit with the station number and designation, the identification number, the name or trademark of the manufacturer, the date manufactured, and stamp indicating conformance with the Specifications. Do not ship any precast unit without complete documentation showing that all materials meet specifications as specified in 305.02 or the Contract Documents; or without complete identification markings as specified in Section 440, Section 905, and Section 915. Place and consolidate at least 6 in. of No. 57 aggregate bedding under the unit. Integral Colored Concrete Structures. Where specified, cast storm water management structures using integral concrete color pigment admixture. Add pigment admixture to the concrete according to the manufacturer’s recommendations. Ensure uniform coloration throughout the structure. Sandblasted Finish. Apply sandblast finish to colored drainage structures. Allow concrete to cure to sufficient strength so that is will not be damaged by blasting but not less than seven days. Apply Class 1 (Brush) finish involving a one pass brush blast which will remove the cement matrix and expose the fine aggregates only. No exposed coarse aggregate is allowed. Meet all local air pollution regulations. Ensure the safety of the workers. Equip each blaster with an air-fed helmet. Ensure that areas immediately adjacent to the sand-blasting operation are cleaned-up. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS Sample Panel. Prior to casting drainage structures with integral concrete color pigment admixture, provide a sandblasted 2 ft x 2 ft x 4 in. sample panel at the construction site for color and finish approval. Ensure subsequent structures requiring integral color match the sample panel. Maintain the sample at the construction site as a basis for comparison with the structures.
305.03.07 Clean Existing Drainage Structures. Clean existing drainage structures and dispose
of the material. Reset and anchor existing grates as directed.
305.04 Measurement and Payment
The payment will be full compensation for all excavation, concrete, masonry, special or precast units, reinforcement, ladder rungs, drip stones, No. 57 aggregate, underdrain stubs, frames, grates and covers, grade and slope adjustments, backfill, and for all material, labor, equipment, tools, and incidentals necessary to complete the work.
305.04.01 Standard Inlets and Manholes will be measured and paid for at the Contract unit price
per each. When a structure exceeds the standard minimum depth an additional payment will be made for the excess depth at the Contract unit price per linear foot for the pertinent Vertical Depth item.
305.04.02 Standard End Walls, Headwalls, End Sections, and Special Structures will be measured
and paid for at the Contract unit price per each. 305.04.03 Nonstandard End Walls and other miscellaneous structures such as steps, spring boxes, and junction boxes, constructed using brick masonry or concrete will be measured and paid for at the Contract unit price per cubic yard, unless otherwise specified.
305.04.04 Stormwater Management Risers will be measured and paid for at the Contract unit price
per cubic yard of Concrete Mix 3 which includes gasket, watertight seals, trash racks, orifice plates, low flow and dewatering pipe stubs and safety rails.
305.04.05 No separate or additional measurement will be made for any precast concrete units,
metal, or castings used in the construction of any of the items noted above. 305.04.06 Cleaning Existing Drainage Structures will be measured and paid for at the Contract unit price per each, regardless of type, size, or depth of the structure. 305.04.07 When an existing drainage structure is to be removed and replaced with a new drainage structure in the same location, the cost to remove the existing drainage structure and a section of the existing pipe will be incidental to the cost of the new drainage structure.
305.04.08 Integral colored concrete will not be measured but will be incidental to the applicable
precast or cast in place concrete item. The payment will include integral concrete color pigment admixture, sandblast finish, clean-up and all material, labor, equipment, tools and incidentals necessary to complete the work. 306 — UNDERDRAINS, SUBGRADE DRAINS, AND SPRING CONTROL CATEGORY 300 DRAINAGE SECTION 306 — UNDERDRAINS, SUBGRADE DRAINS, AND SPRING CONTROL
306.01 Description
Construct underdrains, subgrade drains, underdrain for spring control, underdrain pipe outlets, and blind drains using pipe, geotextile, and granular material. Clean existing underdrain outlets.
306.02 Materials
No. 57 Aggregate 901.01 Portland Cement Concrete 902.10, Mix No. 2 Pipe Section 905 Geotextile, Class as specified Section 919 Securing Pins or Staples 919.03 Flexible Delineator Post and As approved by the Office of Rodent Screens Materials Technology
306.03 Construction
Coordinate the field installation of traffic barrier, signs, lighting, and landscaping with the Engineer to avoid any damage to the underdrains, subgrade drains, or outlet pipes. Correct any damage to the underdrains, subgrade drains, or outlet pipes.
306.03.01 Excavation. Excavate trenches to the specified dimensions and grade. Ensure that the
sides and bottom of trenches are smooth and uniform to prevent tearing of the geotextile when backfilling. For excavated material, refer to 402.03.01.
306.03.02 Geotextile. Place geotextile when specified. Place it with the machine direction
parallel to the longitudinal direction of the trench. Ensure that it is of sufficient width to completely enclose the underdrain trench, including specified overlaps. Place the geotextile tightly against the underdrain trench to eliminate voids beneath the geotextile. Avoid wrinkles and folds. Maintain at least a 24 in. overlap at joint ends or breaks. Pin joints and overlaps to securely hold the geotextile in place until placement of the cover material. Pin longitudinal joints, overlaps, and edges no more than 50 ft on center. 2025 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS