4-1 Division 4 – Drainage Features
Section 401. Pipe Culverts ................................................................................ 4-3 Section 402. Storm Sewers ............................................................................. 4-14 Sectio n 403. Drainage Structures .................................................................... 4-24 Section 404. Underdrains ................................................................................ 4-32 Section 405. Pump Station Construction ......................................................... 4-38 Section 406. Precast Three-Sided, Arch, and Box Culverts ............................ 4-39
4-2 Notes
4-3 Section 401. Pipe Culverts
401.01. Description This work consists of constructing pipe culverts of the size and class required, including excavation, bedding, and backfill. The following terms apply to this section: Type HE. An elliptical pipe placed with the major axis in the horizontal direction. Type VE. An elliptical pipe placed with the major axis in the vertical direction. 401.02. Materials Provide materials in accordance with the following: Granular Material, Class II, III, IIIA ........................................................ 902 Aggregate, 6A, 17A, 34R , 46G ............................................................ 902 Asphaltic Materials ................................................................................ 904 Culvert Pipe .......................................................................................... 909 Sealers for Culvert Joints ...................................................................... 909 Steel Pipe (for jacking in place) ............................................................. 909 Drainage Marker Post ........................................................................... 909 Geosynthetic ......................................................................................... 910 Culvert, Downspouts ............................................................................. 909 Concrete, Grade 3500 ........................................................................ 1004 Mortar, Type R 2 ................................................................................. 1005 Select pipe sections and joint assemblies for use in culverts from the Qualified Products List. Provide grout for jacked-in -place steel pipe that consists of a mixture of Portland cement and no greater than 50 % sand by volume. Pipe Culverts. Pipe culverts are divided into six classes , as specified in Table 401-1. Provide the type of culvert material indicated on the plans if shown. If the contract specifies only the size and class of the culvert, select and provide an alternative culvert pipe allowed in Table 401-1. A higher strength or greater thickness of culvert may be substituted for the minimum strength or minimum thickness required. MDOT Standard Specifications for Construction Section 401
4-4 Table 401- 1: Pipe Alternatives for Culvert Classes
Type of Pipe Culvert Class ( depth of c over, feet(a)) Class A Culvert (1–10)(b)(c) Class B Culvert (>10–16) Class C Culvert (>16–23) Class D Culvert (>23–33)(c) Class E Culver t (1–3)(c)(d) Class F Drive Culvert(e) Reinforced concrete(f) II III IV V IV II Non-reinforced c oncrete(g) 1 3 No No No 1, 3(h) Corrugated and spiral r ibbed al -alloy Yes Yes Yes Yes No Yes Corrugated and spiral r ibbed s teel Yes Yes Yes Yes No Yes Dual-wall polymer -precoated galvanized steel Yes Yes Yes Yes No Yes Smooth -lined c orrugated plastic (CPE)(i)(j) Yes(k)(l) Yes(l)(m) No No No Yes(k)(l) Corrugated polyvinyl c hloride (CPV)(n) Yes(k)(l) Yes(l)(m) No No No Yes(l)
a.Cover, including the pavement structure, is defined as the height of fill above the top of the pipe measured to final grade.
b.Class A culvert applies when the culvert is outside the influence of proposed pavement or is beneath the influence of propose d pavement and the depth of cover is >3 feet but ≤ 10 feet.
c.Special design is required for fill heights <1 foot and >33 feet.
d.Class E culvert applies when the culvert is beneath the influence of proposed pavement and the depth of cover is 3 feet or less.
e.Class F culvert applies for driveway culverts (residential and commerci al).
f.Roman numerals refer to the class of reinforced concrete pipe in accordance with AASHTO M170.
g.Arabic numerals refer to the class of nonreinforced concrete pipe in accordance with AASHTO M86.
h.Nonreinforced concrete pipe Class 1 is allowed f or Class F culverts with a depth of cover of up to 10 feet. Nonreinforced concrete pipe Class 3 is allowed for Class F culverts with a depth of cover from 10 to 16 feet.
i.Provide CPE in accordance with AASHTO M294, Type S polyethylene pipe.
j.At least 2-foot cover if the culvert is outside the influence of proposed pavement (measured from top of pipe to final grade)
k.Allowed only for 36 -inch -diameter pipe and under for CPE and CPV pipes. At least 3 feet of cover.
l.Refer to the Class A, B and F Bu ry Plastic Pipe Qualified Products List for approved manufacturers and products.
m.Allowed only for 12 - to 24 -inch -diameter CPE and CPV pipes.
n.CPV must conform to AASHTO M304. MDOT Standard Specifications for Construction Section 401
4-5 401.03. Construction
A.Excavation and Culvert Bedding . Excavate in accordance with subsection 206.03.A. Construct pipe culvert bedding using granular material Class IIIA. Place bedding at least 4 inches deep and uncompacted for the entire length of the culvert. Where rock or hardpan is encountered, excavate the trench to at least 6 inches below the proposed bottom of the pipe; place bedding using uncompacted granular material Class IIIA. Where unstable soil conditions or obstructions other than rock require excavation of the trench below the elevation detailed on the plans , undercut, backfill, and compact the trench as directed by the Engineer. Use 6A, 17A, 34R , or 46G aggregate as backfill material for undercutting due to unstable soil conditions. Use 34R aggregate for bedding material instead of granular material Class IIIA. Place the backfill up to 4 inches below the proposed bottom of the pipe. The completed work will be paid for as trench undercut and backfill according to subsection 402.04.E.
B.Repair of Damaged Coated Surfaces. Repair coated culvert surfaces damaged during pipe transport ation, handling, or install ation at no additional cost to the Department. Repair galvanized culvert surfaces in accordance with subsection 716.03.E or as approved by the Engineer . Repair other coated culvert surfaces as directed by the Engineer.
C.Laying and Jointing Pipe . Lay culverts as shown on the plans with be lls or grooves upgrade and ends fully and closely jointed. Provide a full, firm bearing throughout the length of the culvert. Wrap all pipe joints with geotextile blanket. Use geotextile at least 36 inches wide, and center it on the joint. Overlap the ends of the geotextile blanket at least 12 inches. Remove and re-lay culvert sections showing signs of settlement or poor horizontal or vertical alignment as determined by the Engineer. Remove, replace, and mandrel test culverts damaged by the Contractor ’s operations if required by the Engineer. Correct settled, misaligned, or damaged culvert sections at no additional cost to the Department.
1.Corrugated Plastic Pipe (CPE and CPV). Provide homing marks on CPE and CPV pipe sections and joint material to show the correct alignment of the pipe sections and joint material during field installation. After the trench backfill and compaction are complete, the Engineer will select at least 50 % of the installed length of each size of CPE and CPV pipe for deformation testing. Provide the labor and equipment required to complete the testing. MDOT Standard Specifications for Construction Section 401
4-6 Unless otherwise approved by the Engineer, perform the mandrel test
within 10 work days prior to pavement surfacing or completion of final grade. Use a nine-point mandrel with an effective diameter of 95% of the nominal pipe diameter. Provide the Engineer with a proving- ring to verify the mandrel size. Pull the mandrel through the pipe by hand using non-mechanical means and without damaging the pipe. The Contractor may use laser profile technology to measure deflection as an approved alternative to mandrel testing. Remove and reinstall or replace pipe with a nominal diameter reduced by at least 5% at no additional cost to the Department. Reinstall only undamaged pipe. Do not reinstall pipe without the Engineer ’s approval. The Contractor is responsible for all expenses and delays due to the replacement of deformed or damaged pipe.
2.Concrete Pipe . Install reinforced concrete elliptical pipe with the longer axis placed horizontally unless otherwise required. Install Type HE elliptical pipe with the longer axis within 5 degrees of the horizontal. Install Type VE elliptical pipe with the longer axis within 5 degrees of the vertical. Install circular concrete pipe with elliptical reinforcement so the lift holes or manufacturer ’s marks are on the top of the pipe. Place pipe so the lift holes or manufacturer ’s marks, designating the top and bottom of the pipe, are not more than 5 degrees from the vertical plane through the longitudinal axis of the pipe. After installing the pipe, seal the lift holes with concrete plugs and wa terproof.
3.Metal Pipe . Provide metal pipe with helical corrugations with a continuous lock seam in accordance with subsection 909.05. The use of dissimilar types of base metal (steel or aluminum alloy) or dissimilar types of coat ings on steel (zinc or aluminum) in a single line of pipe is prohibited. Construction between dissimilar metal type pipes is not allowed unless a drainage structure is used to transition between the two dissimilar type metals. Changing materials at the drainage structure is allowed if the roughness coefficients have been adjusted accordingly. Use coupling bands of the same base metal and coating metal as the pipe.
4.Extending Culverts. When extending a pipe culvert , cast a concrete collar at least 3 inches thick and extending 6 inches on each side of MDOT Standard Specifications for Construction Section 401
4-7 the joint. Wrap the connecting joint with a 36-inch-wide geotextile strip
centered on the joint. When extending an existing corrugated steel pipe with a corrugated steel pipe, a dimple band at least 24 inches wide wrapped with geotextile blanket instead of a concrete collar on the first connection is allowed if the existing culvert is in good condition. Other methods of connecting to the existing pipe require approval of the Engineer before construction . Provide joints tested in accordance with Michigan Test Method (MTM) 723 for the remaining joints of the extension.
D.Backfilling. Backfill in accordance with the MDOT Standard Plan R -83 series and as shown on the plans. Place backfill equally on opposite sides of the pipe at the same time and in layers no greater than 10 inches deep or half the diameter of the pipe, whichever is less . Compact each layer to at least 95% of the maximum unit weight. Maintain at least 3 feet of cover unless trimming for final grade. Maintain the line and grade of the culvert during the backfilling operation.
E.Headwalls and End Sections. Protect the ends of the culvert using headwalls or end sections constructed in accordance with details on the plans. Construct headwalls in accordance with section 706. Use precast concrete end sections on concrete culverts in accordance with the MDOT Standard Plan R -86 series. Construct sloped end sections on concrete culverts as required, using metal or concrete, sloped end sections in accordance with the MDOT Standard Plan R -95 series. Use precast or cast -in-place footings for precast end sections or precast sloped end sections as required. Form or place the footings at the locations and to the elevations shown on the plans. Use metal end sections on corrugated metal pipe culverts. Attach metal end sections to the ends of corrugated metal pipe using standard metal bands or other connecting devices as shown on the plans or approved by the Engineer. Provide and install toe plates on the metal end sections if shown on the plans. Use either precast concrete or metal end sections on CPE. Plastic end sections are prohibited. Fasten end sections to the pipe as recommended by the pipe manufacturer or as directed by the Engineer. The Engineer will allow the use of a metal end section that is one size larger in diameter than the CPE. Slip the end section over the end of the pipe and securely fasten, making sure that the portion of the plastic pipe left exposed is less than 3 inches . If using a concrete end section, wrap the joint with a strip of geotextile blanket 36 inches wide and centered on the joint. Overlap the ends of the geotextile at least 12 inches. MDOT Standard Specifications for Construction Section 401
4-8 Provide and install end section grates on designated culvert end sections.
Fabricate end section grates from weldable- grade hot -rolled steel bars, plain or deformed, of the diameter and configuration shown on the plans. Fasten grates securely to the concrete end sections as shown on the plans. Place salvaged end sections in accordance with specifications for placing new end sections. Replace end sections damaged by the Contractor ’s operation during salvaging or replacing operations with the same size end section as the original at no additional cost to the Department. When discharging to waters of the state, p ermanently label all end sections or other points of storm water discharge with “MDOT” or the local agency ’s name in a conspicuous location that will remain visible after construction . Ensure that the marking is located on the interior of flared end sections in approximate alignment with the spring line of the conduit. For precast or cast -in-place concrete headwalls or when the conduit protrudes through a concrete or steel wall, ensure that the marking is located on the exteri or face directly above the pipe or as directed by the Engineer. Refer to the MDOT Standard Plan R -85, R -86, R -88, or R-95 series for specific applications. Labels applied by stenciling utilizing ink, paint , or other surface application are prohibited. The letters “MDOT” or the local agency ’s name must be physically stamped into steel end sections , creating an indention in the material. For concrete headwalls, end sections , and walls , the lettering must be physically inscribed into the material. When the conduit protrudes through a steel sheet pile wall, the letters may be placed on the face of the wall by welding. Individual letters must be legible and each sized to 1½ inches high by 1 inch wide. The depth of the lett ers must be a minimum of 1/4 inch for concrete and 1/8 inch for steel materials. If the letters are placed by welding, the thickness of the weld must be at least 1/4 inch.
F.Drainage Marker Posts. Place drainage marker posts at headwalls and culvert end sections for culverts with a diameter no greater than 36 inches and at outlet endings. Install drainage marker posts at least 2 feet deep or as recommended by the manufacturer.
G.Pipe Culverts Jacked in Place. Jack the culvert into place to the line and grade shown on the plans or established by the Engineer. If jacking pipe under railroad tracks, submit to the Engineer sheeting and bracing plans for the jacking pits for approval by the railroad company. Do not begin excavating the jacking pit until receipt of the approval. MDOT Standard Specifications for Construction Section 401
4-9 Excavate the approach trench so it is large enough to accommodate jacks
and blocking and at least one section of pipe. Lay two rails or sills in the bottom of the trench to keep the pipe at the est ablished line and grade. Minimize excavation ahead of the pipe to prevent caving of the earth. The Engineer will allow attachment of a steel cutting edge or shield to the front section of pipe to form and cut the required opening for the pipe. A steerable pipe jacking shield must be used on the lead pipe. The annular space between the casing and the carrier pipe must be bulkheaded in accordance with subsection 402.03.E and grouted with an Engineer -approved material. Fill voids between the excavation and the pipe using materials and placing methods approved by the Engineer.
1.Obstructions. The Engineer will measure and the Department will pay for the removal of obstructions that require the use of special procedures or tools at the unit price for Obstruction Removal , in accordance with subsection 718.04.D.
H.Steel Pipe Jacked in Place. Jack steel pipe in place to serve as a carrier pipe or casing for a c arrier pipe. Jack steel pipes in place in accordance with subsection 401.03.G. Bulkhead the ends of steel pipe used as casing for carrier pipe in accordance with subsection 402.03.E. The annular space between the carrier pipe and the casing must be complet ely filled with grout approved by the Engineer. Obstructions must be removed in accordance with subsection 401.03.G.1.
I.Steel Casing Pipe. Install steel casing pipe in a trench as shown on the plans. Provide steel casing pipes placed for future use with a t emporary bulkhead at each end to prevent infiltration into the pipe. Obstructions must be removed in accordance with subsection 401.03.G. 8.
J.Disposal of Surplus Material. Take possession and dispose of surplus material in accordance with subsection 205.03.P .
K.Cleanout. Maintain culverts installed on the project. Ensure that they are free of silt, debris, and other foreign matter above the flow line of the drainage course at the time of final acceptance and in accordance with section 209.
L.Video Inspection. Video inspect culverts as specified for sewers in subsection 402.03.J. Video inspection is not required for the foll owing:
1.Driveway culverts;
2.Culvert extensions less than 50 feet; MDOT Standard Specifications for Construction Section 401
4-10 3. New culverts less than 50 feet; or
4.Extensions of existing catch basin leads less than 20 feet.
M.Dewatering and Maintaining Stream Flow d uring Construction . Maintain the stream flow through the existing channel, temporary channel , temporary culvert , or bypass pumping unless approved by the Engineer. Prepare a bypass pumping or bypass flow control plan that complies with the Michigan Department of Environment, Great Lakes, and Energy (EGLE ) permit requirements and the MDOT Standard Plans and submit it to the Engineer for review 10 days before installin g the system. When using a temporary bypass pipe, sluice, or similar structure, provide sediment control structures at the inlet to contain sediment before it enter s the bypass structure. Maintain the sediment control structure to provide adequate flow and sediment removal capacity. Install temporary dams constructed of sufficient size and depth to withhold the expected backwater. Temporary unco ntained material earthen dams are prohibited. Dewater without causing damage to nearby property, foundations, utilities , or pavements and without interfer ing with the rights of the public, owners of private property, pedestrians, motorists , or the work of other contractors. Do not disturb the soil under and next to existing structures during dewatering and temporary pumping operations . The Contractor is responsible for controlling any additional sediment created by C ontractor operations . Do not overload or obstruct existing drainage facilities. 401.04. Measurement and Payment Pay Item Pay Unit Culv, Cl __, __ inch ........................................................................... Foot Culv, Cl __, (material), __ inch .......................................................... Foot Culv, Downspout __ inch ................................................................... Foot Culv, Outlet Headwall, __ inch ......................................................... Each Culv, Reinf Conc Ellip, (shape) Cl __, (rise) inch by (span) inch ........................................................................ Foot Culv, CSP Arch, Cl __, (span) inch by (rise) inch .............................. Foot Culv, Slp End Sect, (slope), __ inch, Longit ..................................... Each Culv, Slp End Sect, (slope), __ inch, Transv .................................... Each Culv, Slp End Sect, Arch Pipe, (slope), (span) inch by (rise) inch, Longit ..................................................................... Each Culv, Slp End Sect, Arch Pipe, (slope), (span) inch by (rise) inch, Transv .................................................................... Each MDOT Standard Specifications for Construction Section 401
4-11 Culv, Slp End Sect, Ellip Pipe, (slope), (rise) inch
by (span) inch, Longit ................................................................... Each Culv, Slp End Sect, Ellip Pipe, (slope), (rise) inch by (span) inch, Transv .................................................................. Each Culv End Sect, (material), __ inch .................................................... Each Culv End Sect, __ inch ..................................................................... Each Culv End Se ct, Footing .................................................................... Each Culv End Sect, Grate ....................................................................... Each Culv, Cl __, __ inch, Jacked in Place ................................................ Foot Steel Casing Pipe, __ inch, Jacked in Place ..................................... Foot Steel Casing Pipe, __ inch, T r Det __ ............................................... Foot Dr Marker Post ................................................................................. Each Culv End Sect, Salv, 30 inch or less ................................................. Each Culv End Sect, Salv, over 30 inch .................................................... Each Outfall Label ..................................................................................... Each
A.Culverts. The Engineer will measure culverts of the diameter, class, or materi al required, by length, excluding the length of end sections as shown on the plans. The unit prices for culverts include the cost of the following:
1.Excavatin g the material down to grade or to the culvert bedding bottom elevation;
2.Dewatering and maintaining the stream flow during construction stages;
3.Providing and placing the culvert and geotextile strip;
4.Providing temporary cover and restraining the pipe to maintain line and grade;
5.Providing, placing, and compacting the backfill;
6.Conducting m andrel testing if required; and
7.Disposing of excess material.
B.Culvert, Jacked in Place. The Engineer will measure Culv, Cl __, __ inch, Jacked in Place of the class and size required, by length, as determined by multiplying the number of units jacked by the commercial laying length. The unit price for Culv, Cl __, __ inch, Jacked in Place includes the cost of excavati ng the pit; providing and installing sheeting, bracing, and other safety devices; providing jacking equipment; drainage and dewatering; and other items associated with the operation. MDOT Standard Specifications for Construction Section 401
4-12 C. Culvert End Sections
1.End Sections . The unit price for Culv, Slp End Sect of the size or type required includes the cost of providing and placing end sections, including longitudinal and cross tubes as detailed in the MDOT Standard Plan R -95 series. The unit price for Culv End Sect of the size or type required includes the cost of providing and placing the end section. The unit price for Culv End Sect, Metal , __ inch includes the cost of providing and placing the end section and toe plate, as shown on the plans or in the MDOT S tandard Plans . If the Contractor provides corrugated plastic pipe, the Department will pay for culvert end sections of the diameter that is required for the culvert even if the Contractor provides a metal end section larger than the nominal diameter of the pipe. The unit pr ice for culvert end sections includes the cost of fastening the end section to the pipe and wrapping the joint with geotextile blanket. The Department will pay for required riprap in accordance with subsection 813.04. The unit price for Outfall Label includes the cost of providing and installing the label as described in subsection 401.03.E .
2.Culvert End Sections, Footing . The Department will pay for footings required for precast concrete end sections as Culv End Sect, Footing . The unit price for Culv End Se ct, Footing includes the cost of the following for the footing as shown on the plans:
a.Excavatin g and forming;
b.Providing and placing the steel reinforcement; and
c.Providing, placing, finishing, and curing the concrete.
3.Culvert End Sections, Salvage. The unit price for Culv End Sect, Salv includes the cost of removing the existing end section, salvaging and storing, and reinstalling end sections.
4.Culvert End Section, Grate. The Engineer will measure Culv End Sect, Grate by each as shown on the plans for the size of grate required.
D.Headwalls. The Engineer will measure and the Department will pay for headwalls as steel reinforcement and concrete, Grade 3500 , in accordance with subsection 706.04. If the Contractor us es precast wingwalls, headwalls, and aprons instead of cast -in-place wingwalls, MDOT Standard Specifications for Construction Section 401
4-13 headwalls, and aprons, the Department will pay for them as the
corresponding pay items for the cast -in-place wingwalls, headwalls, and aprons as required by the contract. The unit price for Culv, Outlet Headwall includes precast outlet headwalls as shown in the MDOT Standard Plan R-85 series and will be paid for by each.
E.Jacked -in-Place Steel Pipe. The Department will not pay separately for jacked -in-place steel pipe that is used at the Contractor ’s discretion to act as a casing for the carrier pipe. The cost of grouting between the carrier and casing pipes is included in payment for the carrier pipe.
F.Steel Casing Pipe. The unit price for steel casing pipe includes the cost of excavation and bac kfill. The Department will pay separately for carrier pipe inserted into a steel casing pipe. The unit price for the carrier pipe includes the cost of casing chocks, inserting the carrier pipe, an d required gro uting.
G.Videotaping Sewer and Culvert Pipe. The Engineer will measure and the Department will pay for videotaping sewer and culvert pipe in accordance with subsection 402.04.
H.Rock Excavation. The Engineer will measure and the Department will pay separately for rock excavation in accordance with subsection 205.04.
I.The unit price for Dr Marker Post includes the cost of providing and installing the post as described in subsection 401.03. F.
J.The unit price for Obstruction Removal will be paid for in accordance with subs ection 718.04.D.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 207–219 of 1,146.