6-18 SECTIO N 604 – DROP INLETS , CATC H BASINS , AND MANHOLES 604.0 1 DESCRIPTION . This work shall consist of the construction, rehabilitation, adjustment, or decommissioning of drop inlets (DIs) , catch basins, and manholes , and the furnishing and placing of cast iron or precast concrete covers. 604.0 2 MATERIALS . Materi als shall meet the requirements of the following subsection s: Granular Backfill for Structures ................................ ................................ ................. 704.08 Manhole Brick ................................ ................................ ................................ ........... 705.01( a) Concrete Masonry Blocks ................................ ................................ .......................... 705.02 Precast Drop Inlets, Catch Basins, and Manholes ................................ ..................... 705.0 3 Mortar, Type II ................................ ................................ ................................ ........... 707.0 1(c) Mortar, Type IV ................................ ................................ ................................ ......... 707.0 1(e) Reinforced Concrete Pipe ................................ ................................ .......................... 710.01 Bar Reinforcement ................................ ................................ ................................ .....713.01 Welded Wire Reinforcement ................................ ................................ ..................... 713.0 3 Structural Steel ................................ ................................ ................................ ........... 714.02 Gray Iron Castings ................................ ................................ ................................ .....715.01(b) Ductile Iron Castings ................................ ................................ ................................ .715.01(c) Treated Timber Curb ................................ ................................ ................................ ..729.05 Unless otherwise specified, cast -in-place co ncrete shall conform to the requirements of Section 541 for Concrete, Class B. Flowable fill shall conform to the requirements of Section 541 for Flowable Fill, Excavatable . Pipe stubs for precast reinforced concrete curb drop inlets shall meet the requirements of Section 601 . The term cast iron, as used in these specification s, or in the names of various pay items, when used in conjunction with covers and frames, shall be und erstood to mean gray iron castings or ductile iron castings. Covers and frames shall be gray iron castings or ductile iron castings. Steps or ladder rungs in drop inlets, catch basins, or manholes shall be plastic, complying with all applicable OSHA dimens ional and structural requirements . Unless otherwise shown on the Plans, the rungs shall be cast into the fresh concrete, except that for precast units, the rungs may be grouted into preformed voids with a non -shrink grout approved by the Engineer after the concrete has cured. 6-19 604.0 3 GENERA L CONSTRUCTIO N REQUIREMENTS . The excavation shall be to the depth shown on the Plans or ordered by the Engineer, and carefully shaped and graded. The bases for drop inlets, catch basins, and manholes may be either pre cast or cast -in-place concrete. For construction of drop inlets, catch basins, or manholes, the bricks used on top of the concrete to adjust the top to the correct elevation shall meet the requirements of Subsection 705.01( a). Unless directed otherwise by the Engineer, when adjusting the elevation of the tops of existing drop inlets, catch basins, sewer manholes, or manholes, the Contractor shall remove all existing bricks and replace them with new bricks meeting the requirement s of Subsection 705.01( a) as part of the work and costs included in Changing Elevation of DIs, Catch Basins, or Manholes , or Changing Elevation of Sewer Manholes. Channels, inverts, and floor areas for sewer manholes shall be constructed of brick and morta r or Class C concrete conforming to Section 541 . Inverts shall have the exact shape of the sewer to which they are connected and any change in size or direction shall be gradual and even . All construction of sewer manholes must be carried out to ensure wat ertight work . Any leaks in manholes shall be repaired to the satisfaction of the Engineer, or the entire structure shall be removed and rebuilt . Leakage testing shall be performed in accordance with Subsection 628.0 9. Prior to rehabilitating or changing th e elevation of any drop inlet, catch basin, or manhole, the Contractor shall completely clean out the interior of the unit, including cleaning at least 12 inches but not more than 24 inches into any openings in the walls for inspection to determine the ext ent of the work that will be required. Except for components cast using the dry cast process, precast concrete components shall not have the forms removed until a minimum compressive strength of 2,000 psi has been achieved . Precast components shall not be moved until two hours after they have been cast and until a minimum compressive strength of 2,000 psi has been achieved. Reinforced precast sections shall not be shipped from the manufacturing facility until the eighth calendar day from the date of manufac ture, except when the supplier provides test results demonstrating that the design strength has been achieved. 6-20 604.0 4 CONSTRUCTIO N OF DROP INLETS , CATC H BASINS , AND MANHOLES .
a.Concrete Drop Inlet, Catch Basin, or Manhole . The concrete walls shall be constructed on the approved base to the lines, grades, and dimensions shown on the Plans or directed by the Engineer. The required courses of brick shall be placed on top of the concrete to the elevation shown on the Plans or directed by the Engineer . After the bricks are laid, the joints on the inside of the brick masonry shall be neatly pointed. The top section may be precast or cast -in-place. The cast iron frame shall be set in the concrete to ps as shown on the Plans . When tops are precast, they shall be placed in a full mortar bed . The grate or cover shall be properly placed in the frame.
b.Precast Reinforced Drop Inlet, Catch Basin, or Manhole . The precast reinforced concrete risers shall be set reasonably close to line and grade on the previo usly placed concrete base . The top section shall be capped with courses of mortared brick. The cast iron frame shall be placed in a full mortar bed on the brick masonry and the cast iron cover or grate shall be placed on top of the frame.
c.Precast Reinf orced Concrete Pipe Drop Inlet . The precast reinforced concrete pipe sections shall be set on a concrete base as shown on the Plans or as directed by the Engineer. A precast concrete cover or a cast iron grate shall be placed as shown on the Plans.
d.Precast Reinforced Concrete Curb Drop Inlet . The precast reinforced concrete curb drop inlet shall be set to the line and grade as shown on the Pla ns or as directed by the Engineer. The brick masonry, concrete top, and grate shall conform to the requirements of Subsection 604.04(a) .
e.Changing Elevation of Drop Inlets, Catch Basins, or Manholes . Existing drop inlets, catch basins, and manholes that are to be altered or adjusted in elevati on of the existing top shall be reconstructed to the required grade using the existing grates, frames, covers, or tops as specified . If the existing grates, frames, covers, or tops are not suitable for reuse, this Contract item shall not be used. 6-21 Shou ld any grate, frame, cover, or top become broken through carelessness on the part of the Contractor, it shall be replaced at the Contractor’s expense. The existing structure shall be dismantled sufficiently to allow elevation adjustment as shown on the Pla ns or as directed by the Engineer . The existing grates, frames, covers, or tops to be reused shall be thoroughly cleaned of mortar before being reused . Any deteriorated brick, mortar, or missing brick in the structure, including any curb portions of the to ps, shall be repaired or replaced by the Contractor. Granite or concrete curbs, curb board, and bituminous fillet disturbed for this work shall be replaced . New treated timber curb board required shall meet the requirements of Subsection 729.0 5. Bituminous fillet shall conform to the applicable requirements of Section 716 for the type of mix specified by the Engineer and, after installation, shall be sealed in accordance with Subsection 616.0 7(d). Concrete curb and granite curb shall conform to the applicable requirements of Section 616 . Where the unit is to be raised and the change in elevation is less than 2 inches, concentric structural steel rings of nominally 1/2 inch thick material properly w elded to the frame may be used. If excavating through paved surfaces is required, the edges of the excavated area shall be saw -cut to a minimum depth of 1 -1/2 inches.
f.Cast Iron Cover with Frame . The covers with frames shall be properly installed at the locations shown on the Plans or directed by the Engineer. Covers for sanitary sewer manholes shall have the word “SEWER” cast into the top surface . Covers for storm sewer manholes shall have the word “STORM” cast into the top surface.
g.Grates . The grates shall be properly installed at the locations shown on the Plans or directe d by the Engineer.
h.Sanitary Sewer Manhole . Sanitary sewer manholes shall be precast sewer manholes of the type and diameter shown on the Plans and shall meet the requirements of Subsection 705.0 3 except that all barrel joints shall contain an O -ring se al. Steps shall meet OSHA requirements for new construction . The exterior of the entire manhole shall be coated with a bitumastic or other watertight sealant meeting the approval of the sewer line owner. All joints between pipes and the manhole shall be made using an approved watertight boot. 6-22 (i) Changing Elevations of Sewer Manholes . Existing sewer manholes that are to be altered or adjusted shall be reconstructed in accordance with Subsection 604.04(e) , except that all exterior surfaces disturbed by the necessary reconstruction shall be coated or recoated with a watertight sealant approved by the sewer line owner. Necessary steps, pipe joints, and barrel joints shall conform to the requirements of Subsection 604.04(h) . The Contractor may be required to provide a specific step to match the existing steps as part of the work and costs included in this pay item.
j.Rehabilitation of Drop Inlets, Catch Basins, or Manholes . Existing drop inlets, catch basins, and manholes that are to be altered, adjusted, or reconstructed shall be constructed to the required grade using existing grates, frames, covers, or tops, if useable, as specified. This work shall belong to one of three classes. Class I shall include all work down to a depth of 3 feet. Class II shall include all work greater than 3 feet in depth down to a depth of 6 feet. Class III shall include all work greater than 6 feet in depth. If the existing grates, frames, covers, or tops are suitable for reuse, but the remainder of the top requires replacemen t, the Contractor shall carefully remove the frame from the existing top and cast a new top using the existing grate, frame, or cover . If the existing grates, frames, covers, or tops are unsuitable for reuse, new ones shall be furnished as required . Unless otherwise specified, the replacement shall match the existing grate, frame, or cover in size and design. Should any useable, existing grate, frame, cover, or top become broken through carelessness on the part of the Contractor, it shall be replaced at the Contractor’s expense. The existing structure shall be dismantled sufficiently to allow rehabilitation as shown on the Plans for completed drop inlets, catch basins, and manholes . Any existing grate, frame, cover, or top to be reused shall be thoroughly cl eaned of mortar before being reused . Any deteriorated brick, concrete, reinforcement, steps, mortar, or missing brick in the structure, including any curb portions of the tops, shall be repaired or replaced by the Contractor as directed by the Engineer. If the rehabilitation proceeds to a point where the culverts or other pipes entering or exiting the unit are within the area of rehabilitation or replacement, the necessary pipe stubs and collars to connect the existing piping to the rehabilitated unit shall be provided and installed by the Contractor . 6-23 Granite, bituminous, or concrete curbs, curb board, and bituminous fillet disturbed for this work shall be replaced . New treated timber curb board shall meet the requirements of Subsection 729.05 . Bituminous fillet shall conform to the applicable requirements of Section 716 for the type of mix specified by the Engineer and, after installation, shall be sealed in accordance with Subsection 616.0 7(d). Concrete, bituminous, and granite curb shall confo rm to the applicable requirements of Section 616 . Where the unit is to be raised and the change in elevation is less than 2 inches, concentric structural steel rings of nominally 1/2 inch thick material properly welded to the frame may be used. Unless oth erwise directed by the Engineer, the Contractor shall saw -cut all pavements to a minimum depth of 1 -1/2 inches.
k.Rehabilitation of Sewer Manholes . Rehabilitation of sewer manholes shall consist of removing the existing top with cover, with or without fr ame, and rehabilitation of the existing unit to a safe and useful structure, satisfactory to the Engineer . If necessary, this pay item shall include the complete reconstruction of the sewer manhole to current standards. This work shall consist of replacing broken or deteriorated bricks, mortar, concrete, reinforcement, frames, and covers with new material s. New barrel sections shall be precast of the type and diameter existing or as shown on the Plans and shall meet all requirements of Subsection 705.0 3 except that all barrel joints shall contain an O -ring. Steps, if required, shall meet OSHA requirements for new construction . The exterior of the entire manhole shall be coated with a bitumastic or other water -tight sealant meeting the approval of the sewe r line owner . All joints between pipes and the manholes shall be made using an approved watertight boot. 604.0 5 CURIN G AND PROTECTION . After the masonry work is completed, it shall be kept moist and protected from the elements in a satisfactory manner for a period of at least 48 hours . Concrete shall be cured in accordance with Subsection 541.1 5. Precast concrete shall be cured using membrane curing compound . The curing compound shall be applied to the concrete surface after finishing, as soon as the free water on the surface has disappeared and no water sheen is visible, but not so late that the liquid curing compound will be absorbed into the concrete . When t he curing compound cannot be applied as specified herein, the manufacturer shall instead immediately begin wet curing the unit until curing compound can be applied . When this method is used in conjunction with the dry -cast process, the curing room shall be kept at 100% humidity until a minimum compressive strength of 2,000 psi has been obtained. 6-24 When the forms are removed prior to 7 days, the exposed concrete surfaces shall be wet with water within one-half hour of form removal and shall be kept wet until the curing compound is applied . Before application, the concrete shall be allowed to reach a uniformly damp appearance with no free water on the surface, and then the compound shall be applied immediately. Precast concrete drainage components shall not be subjected to freezing temperatures prior to attaining the specified 28 -day compressive strength . Components which are exposed to freezing before reaching the required 28 -day compressive strength shall be rejected without further cause . Any additional test ing on the rejected components as determined by the Engineer to gain acceptance will be at the expense of the manufacturer. 604.0 6 BACKFILLING . Backfill material shall meet the requirements of Subsection 704.08 unless otherwise directed by the Engineer. Backfilling shall not begin until the end of the curing period . Backfill material shall be approved by the Engineer and placed in layers not exceeding 6 inches in depth . Each layer shall be thoroughly tamped using mechanical tampers . Special care shall be taken to ensure adequate compaction around the inlet and outlet pipes. 604.0 7 CAP PING DROP INLET S. Drop inlets shall be capped as detailed and at the locations shown on the Plans. Capping shall include saw -cutting existing pavement as necessary, excavating to the required depth to remove the top portions of the drop inlet, placing a steel plate and backfilling. Pavement shall be saw -cut to minimize damage to the adjacent pavement and shall be kept to the minimum required to cap the drop inlet. The steel plate shall be securely placed to the satisfaction of the Engineer and shall be in accordance with Subsection 714.02 . The drop inlet shall be backfilled with granular backfill for structures in accordance with Section 204 . 604.0 8 DECOMMISSIO NING DROP INLETS . Drop inlets shall be decommissioned as detailed and at the locations shown on the Plans . Decommissioning shall include saw -cutting existing pavement as necessary, excavating to the required depth to remove the cover, removal and disposal of covers and grates, filling the drop inlet with flowable fill, and backfilling as necessary. Pavement sha ll be saw -cut to minimize damage to the adjacent pavement and shall be kept to the minimum required to decommission the drop inlet . Inlets and outlets of culverts within the drop inlets to be decommissioned shall be covered in such a manner so as to preven t the flowable fill from entering the culverts. Flowable f ill shall completely fill all voids within the drop inlet . The drop inlet shall be backfilled with granular backfill for structures in accordance with Section 204 . 6-25 604.0 9 METHO D OF MEASUREMENT . The quantities of new Drop Inlets, Catch Basins, or Manholes of the type specified to be measured for payment will be the number of units of the respective types used in the complete and accepted work . and Cast Iron Grate with Frame, Cast Iron Grate , and Cast Iron Cover with Frame, when used and not included in a specific unit, will be measured as the number of each type specified. The quantity of Changing Elevation of DIs, Catch Basins, or Manholes ; Rehabilitating DIs, Catch Basins, or Manholes , Class I; Rehabilitating DIs, Catch Basins, or Manholes , Class II; and Rehabilitating DIs, Catch Basins, or Manholes , Class III; Cap Drop Inlet ; or Decommission Drop Inlet to be measured for payment will be the number of units modified, decommissioned, or capped in the complete and accepted work .
604.10 BASIS OF PAYMENT . The accepted quantities of new Drop Inlets, Catch Basins, or Manholes
will be paid at the Contract unit price per each for each of the specified types . Payment will be full compensation for furnishi ng, transporting, handling, and placing the material s specified, including concrete, concrete risers, top sections, reinforcing steel, steps, mortar, brick, frames, grates, covers, base sections, coatings, pipe stubs, weep holes, underdrain ends, curb board, and bituminous fillets, and for furnishing all lab or, tools, equipment , and incidentals necessary to complete the work . Excavation will be paid for in accordance with Section 204 . The accepted quantity of Changing Elevation of D Is, Catch Basins, or Manholes ; Rehabilitating D Is, Catch Basins, or Manholes , Class I; Rehabilitating DIs, Catch Basins, or Manholes , Class II; and Rehabilitating DIs, Catch Basins, or Manholes , Class III will be paid for at the Contract unit price per each for the specified unit or class . Payment will be full compensation for all n ecessary cleaning of the interior of the unit to determine the extent of the work ; for excavating, cutting of pavement, and backfilling; for removing deteriorated material s and designated material s; for furnishing all material s, including backfill material , concrete, concrete risers, top sections, reinforcing steel, steps, concrete block, brick, mortar, frames, grates, covers, coatings, weep holes , and underdrain ends required for reconstructing the unit as shown on the Plans or directed by the Engineer; and for furnishing all labor, tools, equipment , and incidentals necessary to complete the work . The cost for cutting pavements and excavating around the top of the unit and the bricks to provide room to accomplish the work ; for backfilling around the unit up to the bottom of pavement or the upper surface of the unit top, as appropriate to the individual location ; and the cost of curb replacement will not be paid for directly, but will be considered incidental to Changing Elevatio n of DIs, Catch Basins, or Manholes ; Rehabilitating DIs, Catch Basins, or Manholes , Class I; Rehabilitating DIs, Catch Basins, or Manholes , Class II; or Rehabilitating DIs, Catch Basins, or Manholes , Class III, as applicable. 6-26 When rehabilitation of a D I, catch basin, or manhole requires the installation of a pipe stub and collar and the Contract includes a pay item for the pipe, the pipe stub and collar will be paid for under the appropriate Section 601 or Section 605 pay item in the Contract. If the Co ntract does not include a pay item for the pipe, the pipe stub and collar will not be paid for directly, but will be considered incidental to Rehabilitating DIs, Catch Basins, or Manholes , Class I; Rehabilitating DIs, Catch Basins, or Manholes , Class II; o r Rehabilitating DIs, Catch Basins, or Manholes , Class III, as applicable. The items Sanitary Sewer Manhole ; Changing Elevation of D Is, Catch Basins, or Manholes ; Rehabilitating D Is, Catch Basins, or Manholes, Class I ; Rehabilitating DIs, Catch Basins, or Manholes Class II ; Rehabilitating DIs, Catch Basins, or Manholes and Class III are mutually exclusive . Only one of these items will be paid at any designated location. The item Changing Elevation of D Is, Catch Basins, o r Manholes will include adjusting the elevation of an existing top, including replacement of deteriorated bricks and mortar, only. The item Rehabilitating D Is, Catch Basins, or Manholes, Class I will include adjusting the elevation of the top and all rehabilitation or reconstruction work on an existing unit down to a maximum depth of 3 feet below the elevation of the upper surface of the unit top. The item Reha bilitating D I, Catch Basins, or Manholes, Class II will include adjusting the elevation of the top and all rehabilitation or reconstruction work on an existing unit extending below a depth of 3 feet to a maximum depth of 6 feet below the elevation of the u pper surface of the unit top. The item Rehabilitating D Is, Catch Basins, or Manholes, Class III will include adjusting the elevation of the top and all rehabilitation or reconstruction work on an existing unit extending below a depth of 6 feet below the el evation of the upper surface of the unit top. The items Cast Iron Grate with Frames, Cast Iron Grate, and Cast Iron Cover with Frame, when used and not included in a specific unit, will be paid for at the Contract unit price per each for each type installe d in the complete and accepted work. The accepted quantity of Cap Drop Inlet and Decommission Drop Inlet will be paid for at the Contract unit price for each. Payment will be full compensation for saw -cutting the existing shoulder surfaces; performing any required excavation; protecting the remaining portions of the drop inlet and drainage components; covering inlets and outlets of existing culverts; furnishing and placing steel plates; furnishing and placing flowable fill; backfilling; and for furnishing a ll labor, tools equipment, and incidentals necessary to complete the work. 6-27 Payment will be made under: Pay Item Pay Unit
604.10 00 Concrete Catch Basin with Cast Iron Grate ................................ .............. Each
604.11 00 Concrete Manhole with Cast Iron Cover ................................ .................. Each
604.18 00 Precast Reinforced Concrete D I with Cast Iron Grate .............................. Each
604.20 00 Precast Reinforced Concrete Catch Basin with Cast Iron Grate ............... Each
604.21 00 Precast Reinforced Concrete Manhole with Cast Iron Cover ................... Each
604.22 00 Sanitary Sewer Manhole ................................ ................................ ........... Each
604.2500 Precast Reinforced Concrete Pipe D I with Cast Iron Grate ...................... Each
604.26 00 Precast Reinforced Concrete Pipe D I with Concrete Cover ..................... Each
604.30 00 Precast Reinforced Concrete Curb D I with Cast Iron Grate ..................... Each
604.40 00 Changing Elevation of D Is, Catch B asins, or Manholes .......................... Each
604.41 01 Rehab ilitating DIs, Catch Basins, or Manholes, Class I ........................... Each
604.41 02 Rehab ilitating DIs, Catch Basins, or Manholes, Class II .......................... Each
604.41 03 Rehab ilitating DIs, Catch Basins, or Manholes, Class III ........................ Each
604.42 00 Changing Elevation of Sewer Manholes ................................ ................... Each
604.45 01 Cast Iron Grate with Frame, Type A ................................ ........................ Each
604.4 502 Cast Iron Grate with Frame, Type B ................................ ......................... Each 604.4 504 Cast Iron Grate with Frame, Type D ................................ ........................ Each 604.4 505 Cast Iron Grate with Frame, Type E ................................ ......................... Each
604.49 03 Cast Iron Grate, Type C ................................ ................................ ............ Each
604.55 00 Cast Iron Cover with Frame ................................ ................................ ......Each
604.56 00 Cast Iron Cover with Frame, Sewer ................................ .......................... Each
604.60 00 Cap Drop Inlet ................................ ................................ ........................... Each
604.65 00 Decommission Drop Inlet ................................ ................................ ......... Each
6-28 SECTIO N 605 – UNDERDRAINS 605.0 1 DESCRIPTION . This work shall consist of constructing drainage systems using underdrains, underdrain outlets, flushing basins, and risers. 605.0 2 MATERIALS . Materials shall meet the requirements of the following subsection s: Granular Backfill for Structures ................................ ................................ ................. 704.08 Drainage Aggregate ................................ ................................ ................................ ...704.16 Corrugated Polyethylene Pipe (CPEP) ................................ ................................ ......710.03 Polyvinyl Chloride (PVC) Plastic Pipe ................................ ................................ ......710.0 5 Corrugated Steel Pipe, Pipe Arches , and Underdrains ................................ .............. 711.01 Corrugated Aluminum Alloy Pipe, Pipe Arches, and Underdrains ........................... 711.02 Gray Iron Castings ................................ ................................ ................................ .....715.01(b) Geotextile for Underdrain Trench Lining ................................ ................................ ..720.05 If the Contract does not specify a particular type of underdrain or carrier pipe, the Contractor may furnish underdrain and carrier pipe of the diameter indicated and in any one of the following material s:
a.Corrugated steel
b.Corrugated aluminum alloy
c.Corrugated polyethylene
d.PVC plastic Each system of underdrain, carrie r pipes, and underdrain risers shall be constructed of the same material . 605.0 3 PROTECTIO N OF MATERIALS . Corrugated polyethylene or PVC plastic pipe stored on the job site prior to use shall be protected from pr olonged exposure to sunlight. The Engineer may require impact or other strength tests of the pipe prior to installation when ultraviolet light degradation is suspected. 605.0 4 INSTALLATION .
a.Excavation . Trenches for underdrain shall be excavated to the dimensions and grade shown on the Plans or as directed by the Engineer. The surface of the trench shall be prepared to a smooth condition free of debris, depressions, or obstructions which may damage the geotextile.
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 792–801 of 1,380.