4-24 Section 403. Drainage Structures
403.01. Description This work consists of adjusting, constructing, or temporarily lowering drainage structures and cleaning existing drainage structures and leads as directed by the Engineer. Drainage structures include manholes, catch basins, leaching basins, inlets, and drop inl ets. Drainage Structure. Includes concrete footing or precast sump. Used for access to new or existing sewers with a diameter no greater than 48 inches. Manhole Base, Type 1 or Type 2, and Manhole Riser. Used for access to new or existing sewers with a diameter of at least 48 inches. Manhole Base Type 1 may be substituted for Precast Manhole Tees. Precast Manhole Tee and Manhole Riser. Used for access to new sewers with diameters of at least 42 inches. Manhole Base, Type 1 or Type 2, and Manhole Riser. Used for access to new or existing sewers with a diameter of at least 48 inches. Manhole Base Type 1 may be substituted for Precast Manhole Tees. 403.02. Materials Provide materials in accordance with the following sections : Granular Material Class II, III ................................................................ 902 Steel Reinforcement ............................................................................. 905 Miscellaneous Metal Products .............................................................. 908 Castings ................................................................................................ 908 Culvert, Sewer Pipe, and Box Sections ................................................ 909 Geosynthetics ....................................................................................... 910 Masonry Units ....................................................................................... 913 Concrete, Grade 3000 ........................................................................ 1004 Mortar Type R -2 .................................................................................. 1005 Provide cast -in-place or precast concrete construction for sanitary sewer manholes. Provide structural steel plate, at least ½ inch thick, for temporary lowering of drainage structures that span 72 inches or less. Verify that plates cover the entire drainage structure with a bearing surface of at least 12 inches. For plates that span greater than 72 inches , submit structural calculations prepared by a Professional Engineer licensed in the State of Michigan to the Engineer . MDOT Standard Specifications for Construction Section 403
4-25 Provide leveling course hot mix asphalt (HMA) for patching during the
temporary lowering operations or other HMA mixture as approved by the Engineer. 403.03. Construction
A.Constructing, Adjusting, and Temporary Lowering of Drainage Structures, Precast Manhole Tees, Manhole Bases, and Manhole Risers
1.Excavation. Excavate for constructing, adjusting, and temporarily lowering drainage structures, precast manhole tees, manhole bases , and manhole risers in accordance with subsection 206.03.A .
2.Concrete Construction. Construct concrete portions of drainage structures in accordance with subsection 706.03. Do not cast drainage structures if the concrete temperature is above 90°F.
3.Placing Brick and Block Mason ry. Do not place masonry with mortar when the ambient air temperature is 36°F or less unless approved by the Engineer. Remove and replace work damaged by frost. Apply a ½ -inch-thick plaster coat of mortar to the outer surface of structures and to the inner surface below the outlet flow line on catch basins with traps or sumps. Place the first set of bricks or blocks on a full bed of mortar. Lay brick or block in courses with uniform mortar joints ½ inch thick within ⅛ inch of depth. Stagger joints by half the length of the brick or block on adjoining courses. Place courses level unless otherwise required. Strike and point joints so the exposed surface is smooth. Rake joints and wet brick or block before placing the plaster coat. Allow the brick or block surface to dry to provide for proper bonding of the plaster coat. Wet the bric k. Allow the brick surface to dry to allow the brick and mortar to bond. Use of broken or chipped brick on the faces of the structure is prohibited. Provide a course made of headers at least every seventh course. Make closures with brick lengths no less than the width of a whole brick.
4.Precast Reinforced Concrete Units. Use poured-in -place concrete in accordance with subsection 403.03.A.2 or precast concrete footings. Construct precast reinforced concrete units in accordance with the contract. Seal the joints with mortar in accordance with subsection 403.03.A.3, or use butyl rubber sealant that conforms to ASTM C990. Support precast concrete footings on a 6-inch subbase of compacted granular material Class II. MDOT Standard Specifications for Construction Section 403
4-26 5. Steel Reinforcement. Install steel reinforcement in accordance with
subsection 706.03.
6.Inlet and Outlet Pipes. Place and compact backfill around the manhole base or sump to provide bedding for inlet and outlet pipes. Extend inlet and outlet pipes through the outside wall surface of the manhole a sufficient length to allow for pipe connections. Construct masonry around pipes and seal with mortar or other product approved by the Engineer to prevent leakage.
7.Backfilling. Backfill in accordance with subsection 401.03.D . Stage backfilling to coordinate with the construction sequencing of the structure as necessary .
8.Temporary Lowering of Drainage Structures . Lower drainage structures before milling the pavement. Record the location of the structure so each cover can be reinstalled at its original location. Remove the existing frames and covers and match mark them for later identification and placement. Salvage and safely store frames and covers. Repair the existing structure to allow uniform contact of the steel plate to the top of the structure. Place and compact the HMA for patching in accordance with section 501.
9.Protection during Construction. Install inlet protection devices in accordance with section 208 and as approved by the Engineer when working around the drainage structure.
B.Drainage Structure Covers. Provide and install new covers, including frames and grates, on new or existing structures as required. Place castings on a full mortar bed.
C.Adjusting Drainage Structur e Covers. Adjusting drainage structure covers applies when the new elevation of the cover requires a vertical change of no greater than 6 inches. Before placing the HMA top course or overlay, make final adjustments to drainage structure covers within the HMA pavement section if only applying one course. Adjust the cover to the required elevation by supporting it on one of the following:
1.Metal ring adjustor ;
2.Precast concrete adjusting ring;
3.Masonry in a full mortar bed; or
4.Alternate adjustor selected from the Qualified Products List. MDOT Standard Specifications for Construction Section 403
4-27 Hold adjusted covers in place. Remove and replace the adjacent
pavement, curb, or curb and gutter to match the existing grades or the required new elevations.
D.Additional Depth of Adjusting Drainage Structures. Additional depth of adjusting drainage structure covers applies when a drainage structure cover is adjusted more than 6 inches from the existing cover elevation due t o a change in elevation of the roadway or when alterations to the drainage structure exceed 6 inches regardless of the change in cover elevation. Remove damaged or unsound portions of the structure as directed by the Engineer and adjust as required.
E.Draina ge Structure Taps. Make connections to existing drainage structures owned by counties, municipalities, or drain commissions in accordance with the owner ’s regulations and the contract. If a conflict exists between the owner ’s regulations and these specific ations, the owner ’s requirements take precedence. If tapping an existing drainage structure, cut an opening into the receiving structure at least equal to the outside diameter of the inlet pipe plus 6 inches and insert the pipe. Pack a layer of mortar at least 3 inches thick around the inlet pipe and strike smooth with the inner wall of the receiving structure. Repair or replace existing drainage structure damaged by Contractor operations during tapping at no additional cost to the Department. Tap directly to a sewer or culvert in accordance with subsection 402.03.D .
F.Cleanout. Maintain catch basins, manholes, leaching basins, and inlets installed on the project. Ensure that installed catch basins, manholes, leaching basins, and inlets are free of silt, debris, and other deleterious material at the time of final acceptance.
G.Cleaning Existing Drainage Structures and Leads. Before the Contractor starts work, the Engineer will determine the condition and identify the areas on the project that require c leaning of existing drainage structures and leads. First, clean the downstream drainage structure nearest the trunk sewer and place a temporary bulkhead so the trunk sewer remains clear. Clean upstream drainage structures and leads only after cleaning and bulkheading the downstream drainage structure. Clean the drainage structures and leads of sand, silt, and debris and prevent further contamination of the leads. MDOT Standard Specifications for Construction Section 403
4-28 Dispose of the waste generated from the drainage structure or drainage
structure lead cleanout operation using either Disposal Alternat ive A or Disposal Alternat ive B in accordance with this subsection. If the Contractor suspects the waste generated is non-hazardous contaminated material or hazardous contaminated material, notify the Engineer. If testing shows the material is a hazardous waste as defined in Part 111 , Hazardous Waste Management , of the Natural Resources a nd Environmental Protection Act (Michigan Compiled Laws [ MCL ] 324.11101 et seq. ), immediately notify the Engineer .
1.Disposal Alternat ive A
a.Solid Waste Phase. Solid waste disposal rules require that the waste have no releasable liquids. Dispose of the solid waste at a Type II landfill. The landfill may require testing before accepting the waste. Provide disposal documentation from the Type II landfill to the Engineer.
b.Liquid Waste Phase. Dispose of the liquid waste using one of the following options: Option 1 – Evaporate the liquid waste by use of drying beds, decanting stations, or similar systems that contain the solids during evaporation. Option 2 – Place liquid waste in a sanitary sewer system with the sanitary sewer owner ’s approval. Provide a copy of the owner ’s approval to the Engineer. Option 3 – Pump the majority of clear liquid from the drainage structure and leads without disturbing the solids. Discharge the clear liquid to:
i.A sanitary sewer or combined sanitary and storm system with the sewer owner ’s approval; ii. The curb and gutter such that it re-enters and is completely contained within the storm sewer s ystem and does not directly discharge into the waters of the state ; or iii. An area of undisturbed, well -vegetated ground at a rate that does not result in excessive ponding, runoff, or soil erosion. Dispose of the remaining solid and liquid phase as waste using Disposal Alternat ive A, either Option 1 or Option 2, or Disposal Alternat ive B.
2.Disposal Alternat ive B. Use a Licensed Liquid Industrial Waste Hauler to transport the waste generated and dispose of it in MDOT Standard Specifications for Construction Section 403
4-29 accordance with Part 121, Liquid Industrial By -Products, of the Natural
Resources and Environmental Protection Act (MCL 324.12101 et seq.). Provide the Engineer with a copy of the transport manifest. 403.04. Measurement and Payment Pay Item Pay Unit Dr Structure, __ inch dia .................................................................. Each Dr Structure, Add Depth of __ inch dia, 8 foot to 15 foot ................... Foot Dr St ructure, Add Depth of __ inch dia, more than 15 foot ................ Foot Drop Inlet, Type __ ........................................................................... Each Mh, Precast Tee, Cl __, __ inch ....................................................... Each Mh Base, __ inch, Type __ ............................................................... Each Mh Riser ............................................................................................ Foot Dr Structure Cover, Type __ ............................................................. Each Dr Structure Cover, Adj, Case __ ..................................................... Each Dr Structure, Adj, Add Depth ............................................................. Foot Dr Structure, Tap, __ inch ................................................................. Each Dr Structure, Temp Lowering ............................................................ Each Dr Structure, Cleaning ...................................................................... Each Dr Structure Lead, Cleaning, __ inch ................................................ Foot
A.Drainage Structures Excluding Drop Inlets . The Engineer will measure the depth of drainage structures, with the excepti on of drop inlets, from the top of the masonry to the top of the concrete footing. The unit price for Dr Structure of the diameter required includes the cost of concrete footing and no greater than 8 feet of the drainage structure depth. The unit price for Dr Structure includes the cost of temporary or final grade adjustments of the structure. The unit price for Dr Structure, Add Depth, 8 foot to 15 foot of the diameter required includes the cost of drainage structure portions greater than 8 feet deep but no greater than 15 feet deep. The unit price for Dr Structure, Add Depth, more than 15 foot of the diameter required includes the cost of drainage structure portions greater than 15 feet deep. The unit price for new structures includes the cost of cleaning new drainage structures.
B.Drop Inlets . The Engineer will measure drop inlets as units, of the type required, regardless of depth. The Department will pay separately for pipe leading from the drop inlet to a sewer or catch basin. The cost of pipe from drop inlets, Type 1, is included in the unit price for related sewer pay items in accordance with MDOT Standard Specifications for Construction Section 403
4-30 subsection 402.04. The cost of pipe from drop inlets, Type 2, as shown in
the special detail , is included in the unit pri ce for the related sewer pay item. The Department will pay for a sewer tap or drainage structure tap in accordance with subsection 402.04 only if tapping the sewer or encased sewer into an existing drainage system is required.
C.Manhole Base and Riser . The E ngineer will measure Mh Riser vertically from above the collar of the Mh, Precast Tee or above the Mh Base to the top of the riser. The unit price for Mh Base, Type 1 includes the cost of cutting access holes in the sewer. If the Contractor uses Mh Base, Type 1 in place of Mh, Precast Tee, and the contract does not include the pay item Mh Base, Type 1, the unit price for Mh, Precast Tee includes the cost of installing a Type 1 manhole base.
D.Drainage Structure Covers. When new covers are placed on existing structures, the Engineer will measure and the Department will pay for Dr Structure Cover, Adj, Case __ in addition to the new cover. The unit price for Dr Structure Co ver, Adj, Case 1 includes the cost of the following:
1.Sawcutting existing pavement, curb, and curb and gutter;
2.Adjusting the cover up or down no greater than 6 inches; and
3.Removing and replacing pavement adjacent to the adjusted cover in accordance with the MDOT Standard Plan R -37 series. The Department will pay separately for removing and replacing curb and gutter adjacent to the adjusted structure. The Department will pay only for Dr Structure Cover, Adj, Case 2 for structure adjustments located outside existing pavement, curb, and curb and gutter. The unit price for Dr Structure Cover, Adj of the cas e required includes the cost of repairs for uniform contact of temporary steel plate to the top of structures. The Engineer will measure Dr Structure, Adj, Add Depth of the required diameter and depth beginning 6 inches from the level of the existing structure, in the direction of adjustment, to the limit of the additional adjustment depth. If the contract includes a pay item for Dr Structure, Adj, Add Depth , the contract will also include a pay item for Dr Structure MDOT Standard Specifications for Construction Section 403
4-31 Cover, Adj of the case required. The unit price for Dr Structure, Adj, Add
Depth includes the cost of drainage structure taps within the limits of the adjustment. The Department will pay for drainage structure taps outside the limits of the adjustment as Dr Structure, Tap . The Department will pay for taps to existing sewers as Sewer Tap of the size required, in accordance with subsection 402.04.
E.Drainage St ructure, Temporary Lowering . The unit price for Dr Structure, Temp Lowering includes the cost of the following:
1.Match marking;
2.Removing, salvaging, and transporting castings to and from the site;
3.Storing the existing structure castings;
4.Plating the structure;
5.HMA patching; and
6.Removing the plate and HMA patching materials for final adjustment. The Department will p ay separately for the final adjustments to drainage structures. The unit price for Dr Structure Cov er, Adjust, Case 1 includes the cost of removing pavement to lower the structure. The cost of repairs is included in the unit price for the related drainage structure adjustment pay item.
F.Cleaning Existing Drainage Structures and Leads. The unit price for Dr Structure, Cleaning includes the cost of testing for disposal, hauling, and disposing of generated waste. The unit price for Dr Structure Lead, Cleaning of the size required includes temporary bulkheads and the cost of testing for disposal , hauling, and disposing of generated waste. The cost for cleaning out existing sewers, plugged by Contractor operations, is included in related pay items. If not included in the contract, t he Department will pay for disposal of non-hazardous contaminated material and hazardous contaminated material in accordance with subsection 109.05.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 230–237 of 1,146.