Excavation (Minimum Trench Widths) (603.05)
Exterior Coatings and Waterproofing (603.09)
Placement and Compaction Requirements (603.11)
Documentation Requirements – 601 Slope and Channel Protection
Documentation Requirements – 602 Masonry
Documentation Requirements – 603 Pipe Culverts, Sewers, and Drains
Clearing Site and Restoring Damaged Sites (603.10) Documentation
Filed Paving of New or Existing Pipes (603.11) Documentation
The types of pipe are specified in accordance with their application and intended usage. For a brief description of typical applications see section 603.02. For a more detailed description, see Ohio Department of Transportation’s (ODOT) Drainage Design Manual and the plans.
Type A conduits are sealed culvert cross drains under pavements, paved shoulders, and embankments. These culvert cross drains are used to convey water from one side of the roadway to the other. These culverts can be either smooth lined or corrugated. Type A conduits are under pavement and open at both ends.
Type B conduits are storm sewers under pavements, paved shoulders, and commercial or industrial drives. Storm sewers are used to convey water from one manhole or a catch basin to the other. Storm sewers are always smooth lined. Type B conduits have one or both ends closed with a drainage structure.
Type C conduits are storm sewers not under pavements or paved shoulders and commercial or industrial drives. Like the Type B conduits these conduits are connected to a manhole or catch basin and are always smooth lined. Type C conduits have one or both ends closed with a drainage structure.
Type D conduits are culverts placed under residential driveways or bikeways. These conduits can be either smooth lined or corrugated.
Type E conduits are farm drain headers in or outside the right-of -way or used for ditch elimination beyond the paved shoulder. These conduits can be either smooth lined or corrugated.
Type F conduits are other miscellaneous pipe where a butt joint or a short length jointed pipe would be undesirable. Outlets for underdrain or farm drains, house drain connections, pull box drains, or for steep portions of a median outlet under an embankment are examples of Type F applications. These conduits can be either smooth lined or corrugated.
The soil and granular embankment requirements are listed in CMS 203.02R. Recycled asphalt is not allowed for use as bedding and backfill material. If there is any doubt about the suitability of the proposed soil or granular embankment, send a sample to the district laboratory for classification.
The Structural Backfill material requirements are listed in CMS 703.11. Type 1 is an Item 304 material without the fracture count requirement. Type 2 is a sand material. The Type 1 and 2 materials are allowed for all bedding and backfill operations. The Type 3 is an open-graded No.57 or No.67 material and is allowed to control severe ground water problems only.
In some cases, the plans designate the use of LSM as bedding and/or backfill material. The requirements for LSM can be found in CMS 613. There are three Types of mixes. Type 1 mix is a mixture of cement, fly ash, sand, and water. The Type 2 mixture substitutes an entrained air additive for the fly ash. The Type 3 mixture is a mixture of fly ash and water. All three mixes may be used, or an alternative mix submitted for approval by the Contractor may be used if the plans do not call out a mix. The alternate mixes shall meet the criteria in CMS 613. Changes in the material type or amount or sand gradation are allowed, as long as the final mix has the required strength, fills the voids, and sets up.
All pipes, including plant inspected and certified materials are inspected for dimensions and condition after being delivered to the project. Where the dimensions fail to comply with the specified tolerances, or where the pipe includes defects described herein or in the specifications, the pipe is not approved for placement on the project.
Concrete pipe and thermoplastic pipe are accepted under the TE-24 system. Under the TE-24 system, the pipes are randomly inspected by an ODOT Inspector at the plant. But not all the pipe pieces are inspected at the plant.
Metal pipe are accepted under the TE-215 certification program. Under this certification program, the pipe is not inspected at the plant. The material is delivered with a certification card.
For further detail on the Certification Program contact the District Testing Engineer or refer to Materials Managements Sampling and Testing Program Manual.
All pipe should be inspected prior to the incorporation into the work. All pipe should be randomly checked for minimum diameters, spans, heights, or dimensions shown in the plans.
Any pipe may be rejected at any time whether approved under the TE-24 system, the certification program, or any other program. This would include material damaged during shipment or placement.
The following is a list of reasons to reject the pipe in the field. Reference is made to the current edition of the Materials Managements Sampling and Testing Program Manual.
1. Fractures or cracks passing through the wall or joints.
2. Minor flaws such as a single crack not exceeding 2 inches (51 mm) length at either end of a pipe, or a single fracture or spall in the joints not exceeding 3 inches (76 mm) around the circumference of the pipe or 2 inches (51 mm) in length into the joint, are not to be considered cause for rejection unless these defects exist in more than 5% of the entire shipment.
3. Defects that indicate imperfect mixing and/or molding. (Honeycombed or open texture).
4. Cracks sufficient to impair the strength, durability, or serviceability of the pipe. Any crack passing through the wall would be sufficient to impair the strength of the pipe because it lacks the reinforcing to resist loading.
5. Damaged ends or manufacturer’s defects that would prevent making a satisfactory joint.
1. Fracture or cracks passing through the wall, except for a single end crack that does not exceed the depth of the joint.
2. Defects that indicate imperfect mixing and/or molding. (Honeycombed or open texture).
3. Exposed reinforcing steel or reinforcing steel without minimum cover, except for spacers and vertical longitudinal wires in the bell and spigot of the pipe joint.
4. Damaged ends or a manufacture defect that would prevent making a satisfactory joint.
1. Accuracy of the span or rise dimensions with internal dimensions varying by more than 1 % or 1½ inches (38mm), whichever is less.
2. Haunch dimensions cannot vary by more than 3/4 inches (19mm) from plan.
3. Wall thickness cannot be less than 1/4 inches (6mm) of the plan dimension.
4. Fractures or cracks greater than 0.01 inches (0.25mm) passing through the slab or walls.
5. Defects that indicate imperfections in proportioning, mixing, or forming.
6. Unsound concrete or spalls can be determined by sounding or by visual inspection. Areas extending completely through the wall or surface area with more than 1 square foot (0.1 square meters) of unsound concrete or spalls are cause for rejection. Smaller areas can be repaired (after inspection) with material meeting the requirements of 705.21 and on an approved list.
7. Honeycomb areas more than 2 square feet (0.2 square meters) or any honeycombing which extends more than one half through the wall thickness. Honeycombing less than 2 square feet (0.2 square meters) can be repaired by grout rubbing.
8. Patching or repairs not authorized by the Department.
9. Exposed reinforcing steel or reinforcing steel lacking minimum cover.
10. Damaged ends or manufactures defects that would prevent making a satisfactory joint.
1. Fractures or cracks passing through the barrel or socket. A single crack at the spigot end of the pipe not exceeding 75 % of the depth of the socket, or a single fracture in the socket not exceeding 3 inches (76 mm) around the circumference or 2 inches (51 mm) lengthwise may be permitted.
2. Chips or fractures on the interior of the pipe exceeding 2 inches (51 mm) in length, 1 inch (25 mm) in width, and a depth of more than 1/4 of the thickness of the shell.
3. Cracks sufficient to impair the strength, durability, or serviceability of the pipe.
4. Any crack passing through the wall of the pipe would be sufficient to impair the strength of the pipe because it lacks the reinforcing to resist loading.
6. Any cuts, punctures, cracks, or separations in the interior or exterior of the pipe.
7. Deviation from true shape (usually out of round by more than 2% of the diameter) or deviation from straight centerline.
8. Any damaged ends or manufacturing defects that would prevent the sealing of the joints.
9. Non-uniform color or texture.
1. Any cuts, punctures, cracks, or separations in the interior or exterior of the pipe.
2. Uneven laps.
3. Deviation from straight centerline.
4. Deviation from true shape (Usually out of round by more than 2% of the diameter of the pipe). Minor repairs such as minor bending of the metal, refinishing the galvanizing, or re-rounding may be allowed.
5. Ragged or diagonal sheared edges.
6. Loose, unevenly lined, or spaced spot welds.
7. Unfinished ends.
8. Bruised, scaled, or broken coating.
9. Excessive dents or bends in the metal.
10. Any damage or manufacturing defects that would impair the jointing of the pipe.
See Standard Drawing DM-1.4
A cut situation (Method A) is defined as a field situation where the top of the trench is above the top of the pipe. This is where the existing ground is above the top of the pipe.
See Standard Drawing DM-1.4
A fill situation (Method B) is defined as a field situation where the top of the pipe is above the top of the trench. In this situation the fill or new embankment is constructed to the spring line of the pipe, and then the trench is constructed.
The specifications require the Contractor to remove the ground water from the trench. This can usually be done by using pumps, deep wells, diversion ditches, or pipes. In some cases, pumping operations will not remove sufficient ground water to construct the project. As a last resort, the Projects Engineer may allow the Contractor to place Structural Backfill Type 3 below the pipe to help relieve the water flow. When permitted, the Structural Backfill Type 3 is only placed below the bottom of the pipe. This material is very porous and should relieve the water problems in most cases. This work is performed at no additional cost to the Department.
When using Structural Backfill Type 3 backfill material, the material on top of the Type 3 Material should be Structural Backfill Type 1 to prevent the fine portion of the surrounding soils or backfill from migrating into the void space in the Type 3 backfill material following construction.
Another alternative to relieving the water to construct the pipe as stated above is to use Item 613 Low Strength Mortar Backfill (LSM) to cut the water off. Sheet piling can also be used to cut the water off. The expense of both of these methods should be carefully evaluated. Unless designated in the plans, the cost of the LSM or sheet piling is the responsibility of the Department.
The foundation of a conduit must uniformly support the conduit during construction and for the life of the conduit. Soft conditions and rock conditions are two situations that are important to evaluate in the field. Soft conditions are the most common situations that come up in the field. In general, if the workers can stand and work in the trench, the foundation is adequate for construction. If the material is too soft, then the Project Engineer should investigate the cause of the problem. Review all available soil borings in the area or dig test pits to find the extent of the soft material. Make certain that the proposed remedy is appropriate for both the construction technique and materials used in the work.
Sand or well-graded aggregate may be used to replace the soft material. Make sure that groundwater issues are addressed (as discussed above). It is rare that there is a need to undercut more than 2 feet (.6m) of material to restore support for the pipe. Corrections of soft conditions within 1 foot (.3m) below the bottom of the trench are at the Contractor’s expense except for undercuts shown in the plans. The correction made below this 1-foot (.3m) depth is the Department’s responsibility. When rock boulders are encountered, they should be removed to at least 6 inches (150 mm) below the pipe. When rock is found under the full length of the pipe, the rock should be removed to a 6 inches (150 mm) average depth below the pipe.
Minimum trench widths are specified to assure that adequate room is provided for the proper placement and compaction of bedding and backfill material below the springline of the pipe and to allow for the proper joining of the pipe sections. Maximum trench widths are not specified for pipes. The Contractor will build to the minimum trench width to save on backfill material. Spot checks of the trench width are required to ensure proper widths, adequate working room and that the specifications are being observed. These checks need to be recorded on CA-P-1 Daily Pipe Inspection Form.
All trench walls shall be as vertical as practical to a height above the pipe.
The first step to determine the minimum required trench width is to determine the span (outside to outside at the widest point) of the pipe. This is easily measured in the field and should be recorded on the CA-P-1 Daily Pipe Inspection Form. Once the span is known, the minimum trench width (W) can be calculated. The following example illustrates a calculation for the minimum trench width.
Given: Plastic Pipe
Span= 38 inches (960 mm)
W = Minimum Trench Width = 1.25 Span+ 1 foot (.3m)
W = 1.25(38”/12”/’(960mm/1000 mm/m)) + 1 foot (.3m)
= 4.958 FT. (1.5m)
See Standard Drawing DM-1.4. The following tables are furnished to reflect the Standard Drawing. There are four different Types of Bedding. The Types of Bedding depends on the type of specified conduit. Table 603.A shows the different Types of Bedding.
Table 603.A – Bedding Types
|
Bedding Type |
Structural Backfill Thickness |
Middle one-third |
|
Type 1 |
6 inches (150mm) |
Do nothing |
|
Type 2 |
6 or 3 inches (150 or 75mm) |
Loosen |
|
Type 3 |
0 inches (0mm) |
Loosen |
|
Type 4 |
0 inches (0mm) |
Do Nothing |
Type 1 bedding is required for all reinforced concrete box sections and 3-sided structures that are placed on a slab.
Type 2 bedding consists of the placement of a minimum depth of 3 or 6 inches (75 or 150mm) of structural backfill. See Table 603.B below for material type, pipe type, and the thickness of bedding required.
Furnish a loosened middle one-third for each case.
Table 603.B – Pipe Type
|
Material |
Pipe Type |
Bedding |
Thickness of Structural Backfill Bedding |
|
706.01,706.02,706.03 |
Type A |
Type 2 |
3 inches (75mm) |
|
706.01,706.02,706.03 |
Type B |
Type 2 |
3 inches (75mm) |
|
706.01,706.02,706.03 |
Type C |
Type 3 |
0 inches (0mm) |
|
706.01,706.02,706.03 |
Type D |
Type 3 |
0 inches (0mm) |
|
All Plastic and Metal |
Type A |
Type 2 |
6 inches (150mm) |
|
All Plastic and Metal |
Type B |
Type 2 |
6 inches (150mm) |
|
All Plastic and Metal |
Type C |
Type 2 |
6 inches (150mm) |
|
All Plastic and Metal |
Type D |
Type 2 |
6 inches (150mm) |
Type 3 bedding is only for Type C and D concrete conduit.
Type 4 Bedding consists of shaping the existing or natural ground to place the pipe. Type 4 bedding is required for only all Type E and F conduits.
The bedding that is extended 30% up around the conduit is compacted by shoveling, spudding, or flooding. It is absolutely critical that the material in this haunch zone (between the flow line of the pipe and the 30% diameter elevation) be compacted to a maximum density and all the voids are filled. The structural performance of a pipe relies significantly on the compaction of the haunch material.
The construction of the pipe should always start at the outlet end of the pipe run. This procedure should only be changed under special conditions. This means that the work will progress up grade, which makes the jointing of the pipe easier. The Contractor is responsible for the accuracy of the pipe alignment and the grading. The Engineer should ensure the work is progressing in accordance with the plan.
All pipe inlets will be a normal fabricated end piece. For concrete pipe the inlet would be the bell section. The design is based on this type of inlet. If the bell is cut off the design is incorrect and flooding will occur. Box culverts are also designed for the bell at the inlet. Metal pipe has a square edge and can be cut to fit. The cut end is then coated to match the pipe coating. Plastic pipe can have either a square edge, or a bell end. Any inlet that does not have a normal fabricated end piece must be replaced.
The Contractor’s surveyor or foreman usually lays out the location and the grade of the pipe. The starting elevation is usually established at the outlet end of the pipe run and carried forward to the inlet end of the pipe run. The pipe grade is established by using a string line, batter boards, or lasers.
When a string line or batter boards are used the following procedure is followed. The plan pipe grade is roughly established by using grade stakes at the surface of the pipe trench or at the bottom of the trench. The grade stakes are placed at 25 feet (7.5m) or 50 feet (15 m) intervals.
The grade stakes by themselves do not offer sufficient control for the Contractor to place the pipe. The stakes are generally offset too far from the pipe installation to be used directly. Longer grade stakes are used to establish the string line or batter board height to establish the actual construction grade line. The Contractor will place batter boards across the pipe trench and then pull a string line over the batter boards. The string line is set in place directly over the pipe centerline at the same slope as the trench bottom and pipe flow line. A level rod or a marked rod is used to measure the correct distance between the string line and the pipe flow line or trench bottom. This rod is used to keep the pipe or trench bottom on grade throughout the pipe run.
On most construction projects a laser is used to maintain the pipe grade. A laser light beam is used in the trench or above the pipe trench. The laser light beam is established at grade directly over the pipe as the string line was used when using batter boards in the example above. Once this grade is established measurements are made to the pipe invert or the trench bottom to hold the grade throughout the construction. This method is the most convenient and is preferred by most Contractors.
Pay particular attention when placing large pipe structures such as concrete boxes. The final grade should be accomplished by raking the granular material with a screed board. The screed board should be as long as the width of the box (Span + 2 times the wall thickness). Then attach a 4 feet (1.2 m) long level to the top of the screed board. Starting at the outlet end, the workers should screed the granular material, filling in low spots and leveling off the high spots. This special attention will expedite the setting of the box sections.
Once the centerline of the box sections is established, a string line or laser should establish the outside of the box sections. The string line or laser is established about 2 inches (50 mm) from the outside of one of the edges of the box sections. Alignment can be easily monitored by measuring over from this line. If a string line is used, then it is usually attached to the footer re-steel.
The setting of the pipe or box starts at the outlet end of the trench, and construction continues to the inlet end (up-grade). It is easier to work upgrade with the help of gravity to hold the pipe or box sections together than to work downgrade. The tongue or spigot (male) end of the pipe or box is always downgrade. The bell or grooved (female) end of the pipe is always up-grade. The construction proceeds this way to minimize the bedding material trapped in the pipe joint and to maximize the hydraulic flow into the pipe or box.
The pipe or box construction may use chains, cables, spud bars, wooden blocks, or pipe pullers to place the sections of pipe together. The type of equipment used depends on the size of the pipe. The Contractor is responsible for placing the pipe or box at the required grade. The final position of the sections of pipe must form a smooth grade. If the Contractor cannot place the box sections together to within 1 inch (25 mm) then the Project Engineer should require the use of winches.
When it is necessary to field cut a pipe, the section cut must have a concrete cradle or collar. The cut section of pipe must not be an end piece. The final joint must be stable. The inlet end must have the groove or bell intact to maximize the hydraulic flow into the pipe or box.
1. Standing water in the trench makes it difficult to determine the evenness of the bedding.
2. Most joint annular spaces are 1/4 inches (6 mm) to ½ inches (12 mm). If the bedding is irregular, lining up the tongue into the receiving bell will be difficult. Because boxes are wide and flat, any irregularities in the bedding can cause the tongue of the box not to be properly started into the bell. If this is apparent before attaching the winches and anchors, pull the box out of the way and check the bedding again.
3. If the trench conditions are unstable, the line and grade cannot be held and the area must be stabilized by the use of drainage (pumps) or the removal of unstable sub-soils.
4. Boxes that do not hang plumb may be caused by improper anchorage location. If using a four-part sling, longer or shorter clevises may help alleviate the problem. Be consistent in hooking the rigging to the box culvert.
5. Take care to ensure that both vertical portions of the tongue get started evenly into the bell of the previously set box to keep from pulling the box into its home position unevenly.
6. If footers or head walls are specified consult the supplier to determine if the actual lay length of the individual boxes plus joint creep will be greater than the culvert length shown in the design plans.
7. The Contractor is responsible for the accuracy of the pipe alignment and the grading. The Engineer should ensure the work is progressing in accordance with the plan.
The flat top and arch top structures require an approved shop drawing prior to installation. These details should be thoroughly examined prior to the installation of the sections.
The placement and jointing of these structures are approximately the same as concrete boxes, with the differences noted below.
The arch and flat top sections are placed on a footing designated in the plans. Newer designs will have the footing at zero grades. If needed, the sections can be placed on Masonite or steel shims to properly align the sections.
Place the sections by crane from the outlet end to the inlet end (Up-grade). The crane holds the sections in place while winches and/or spud bars are used to make the final placement.
When the sections do not completely come together, a gap tolerance of 1 inch (30 mm) per joint is desirable. The most important dimension is the top gap of the joint. The top elevation of the sections of the arch or flat top sections should be at approximately the same elevation. This maximizes the strength of the joint. If the jointing cannot be done successfully, then the use of winches should be considered.
Type A, B, C, D, and F conduits are required to have sealed, banded, bell and spigot, tongue and groove, or bolted joints. Type E conduits are permitted to have open joints.
Corrugated metal pipe joints shall be sealed with coupling bands with bolts. The bands are placed around the first placed pipe and then the second pipe is brought into position. The two pipe sections should be within 1 inch (25 mm). Check the joint to ensure the ribs or dimples line up, then join the sections. The bolts are tightened sufficiently to securely close the band. For large diameter corrugated metal pipe, the band should be hammered in place by the use of a mallet to ensure the seating of the band. The permissible differences between adjacent sections is ½ inch (15mm) for conduits greater than 54 inches (1350 mm) and 0.109 inch (2.77 mm) in wall thickness. The permissible differences between adjacent sections is ¼ inch (7mm) for conduits less than or equal to 54 inches (1350 mm). Strutting is required for conduits greater than 54 inches (1350 mm).
Thermoplastic joints may be sealed with a coupling band or by a gasket bell and spigot joint. The joint will not allow any infiltration by the backfill. Tightened sufficiently, use the cable ties with thermoplastic split couplers, to securely close the band. When bells with locking lugs are furnished place them so that all the detents or lugs lock into the corrugation valleys.
Concrete pipe and clay pipe are required to have sealed joints with one of the following:
1. Sealed bituminous pipe joint filler (CMS 706.10) (commonly known as “bear grease”) is placed to completely fill the joints. After the joint filler is placed, trowel the material for a smoothed finish inside and out in place. It is common for this material to drip off top surfaces, but this should be kept to a minimum.
2. Preformed butyl rubber material (CMS 706.14) may be used. The joint must be primed on both sides prior to the installation of the butyl material. This material is placed completely around the joint. The material will overlap 6 inches (150mm) at the ends. The joint is sealed but the material may not completely fill the joint from the inside to the outside. The joint must be sealed from water and fine infiltration.
3. Resilient and flexible gasket joints (CMS 706.11 for concrete pipe, or CMS 706.12 for clay pipe) may be used.
4. Other materials may be used if approved by the Project Engineer.
1. Epoxy coated reinforced concrete pipe (CMS 706.03) must be sealed with fibrated coal tar joint compound placed in accordance with the manufacturers recommendation. After the joint filler is placed, trowel the material for a smooth finish inside and out in place. The outside of the pipe is completely sealed.
2. If the plans call out resilient and flexible gasket joints conforming to 706.11 or 706.12 then furnish these joints and test them as required.
1. Concrete Boxes are required to have sealed joints with one of the following:
a. Sealed bituminous pipe joint filler (CMS 706.10) (commonly known as “bear grease”) is placed to completely fill the joints. After the joint filler is placed, trowel the material for a smoothed finish inside and out in place. It is common for this material to drip off top surfaces, but this should be kept to a minimum.
b. Preformed butyl rubber material (CMS 706.14) may be used. The joint must be primed on both sides prior to the installation of the butyl material. This material is placed completely around the joint. The material will overlap 6 inches (150mm) at the ends. The joint is sealed but the material may not completely fill the joint from the inside to the outside. The joint must be sealed from water and fine infiltration.
c. Resilient and flexible gasket joints (CMS 706.11 for concrete pipe, or CMS 706.12 for clay pipe) may be used.
d. Other materials may be used if approved by the Project Engineer.
2. Concrete Boxes are required to have the Outside and Inside Surfaces sealed
a. There are no critical joints; each section is independent. The exterior joint gap on the top, the interior sides, and bottom gaps of the Precast Reinforced Concrete Box are filled with CMS 706.02 mortar before placing the membrane waterproofing or joint wrap.
The critical joint is the top exterior. The top exterior joint of the Three-Sided Flat Top sections are designed with a keyway detailed in the shop drawings. This keyway is filled with a non-shrink mortar (CMS 705.22). All other joints see the specification.
There are no critical joints; each section is independent. The joints of the arch sections have a 45-degree chamfer. The external side of the joint shall be cleaned prior to the installation of any sealing material. One continuous section of flexible plastic gasket (CMS 706.14) is placed from the bottom of the leg on one side to the bottom of the leg of the other. The chamfer section is primed at the project site prior to the installation of the flexible plastic gasket (CMS 706.14). The primer is a type that has been recommended by the flexible plastic gasket (CMS 706.14) manufacturer. Each joint, sealed with flexible plastic gasket (CMS 706.14), is covered with a 9-inch (225 mm) wide strip of Type 3 Membrane Waterproofing (CMS 711.29). A primer is placed on the external side of the joint under the area of the Type 3 Membrane Waterproofing. The primer used is as recommended by the Type 3 Membrane Waterproofing manufacturers. The plan or the shop drawing may allow other joint sealers.
Membrane waterproofing is placed in accordance with the plans. Areas of the box, 3-sided flat top, or arch shall be clean prior to the placement of the (CMS 512) Sheet Type 2 Membrane Waterproofing. Place the Sheet Type 2 Membrane Waterproofing in all areas that are in contact with the backfill material. When asphalt is in direct contact with the top of the box sections, or Three-Sided Flat Top sections then use Sheet Type 3 Membrane Waterproofing. No joint wrap is required under the membrane.
Areas of the box, 3-sided flat top, or arch outside the limits of the granular backfill. The epoxy sealer is applied to the top surface and 1 foot (0.3 m) down the legs of the structure. This area includes the joint. The joint wrap is at least 9 inches (230 mm) wide and is one continuous roll per joint. The joint shall be clean prior to the installation of the joint wrap.
Backfill materials are defined as all materials above the bedding material and below the subgrade of the pavement structure or the ground elevation. The backfill materials may be Structural Backfill Type 1 or 2, soil, or granular embankment. These backfill materials are required or an option depending on which type pipe is specified and whether the field situations are a cut or fill.
See Standard Drawing DM-1.4 for details.
Structural Backfill Type 1 and 2 are allowed for all backfill applications. There is an option to switch to a soil or granular embankment at certain heights above the pipe depending whether the pipe is located in a cut or fill. Structural Backfill Type 1 or 2 is required for specific width as measured from the outside diameter of the pipe or structure to the trench wall. The minimum height above the pipe for the Structural Backfill represents the location where the material may change to soil or granular embankment. The height of the Structural Backfill may be less than shown if the subgrade is closer to the top of the pipe than the minimum required. Example: The minimum Structural Backfill height required is 4 feet (1.2 m). If the subgrade elevation were 3 feet (0.9 m) above the pipe, then the height of the Structural Backfill would be 3 feet (0.9 m).
|
Compaction Equipment |
Total Weight of Equipment |
Height above Pipe |
Required Width |
|
No Hoe Rams but Small Equipment |
Less Than or Equal to 1 ton (0.9 metric ton) |
0 to 2 feet (0 to 0.6m) |
3 times span or 12 Feet (3.6m)+ span Whichever is less |
|
Hoe Rams Small Equipment Medium Equipment |
Greater Than or Equal to 1 ton (0.9 metric ton) but Less Than or Equal to 8 tons (7 metric tons) |
Greater Than 2 feet (.6m) but Less Than or Equal to 4 feet (1.2m) |
3 times span or 12 Feet (3.6m)+ span Which Ever is Less |
|
Hoe Rams Small Equipment Medium Equipment Large Equipment |
Greater Than 8 tons (7 metric tons) |
Greater Than 4 feet (1.2m) |
No Restrictions |
In a cut, Structural Backfill Type 1 or 2 is required for Type A and B conduits for a height of 4 feet (1.2 m). See Standard Drawing DM-1.4
In a fill, Structural Backfill Type 1 or 2 is required for a height of 2 feet (0.6 m) above the pipe and for a distance equal to 4 feet (1.2 m), or one span of the pipe, whichever is less (span is measured as the outside diameter of the pipe at the widest point). See Standard Drawing DM-1.4
In the cut and fill situations described above, Soil and Granular Embankment may be substituted above these heights to the subgrade or ground elevation.
Place and compact the backfill in the trench with either Structural Backfill Type 1 or 2, Soil, or Granular Embankment. For these pipe types there are no changes in the width requirements for the trench between cut and fill situations. See Standard Drawing DM-1.4
For Type C and D thermoplastic pipe, Structural Backfill Type 1 or 2 is required for 1 foot (.3m) above the pipe for cuts or fill situations. Structural Backfill may be substituted with soils and/or granular embankment above the 1-foot (.3m) height to the subgrade or ground elevation.
See Standard Drawing DM-1.4
Place and compact the backfill in the trench above the bedding with either Structural Backfill Type 1 or 2, Soil, or Granular Embankment to a height equal to two thirds of the conduit rise then place and lightly place and compact backfill to a height of 1 foot (.3m) above the conduit.
Place the backfill in the trench above the bedding with Granular Material as defined in CMS 605.02. See Standard Drawing DM-1.2.
Long span Structures are defined as Precast Reinforced Concrete Boxes (CMS 706.05), Precast Reinforced Concrete, Flat Top Three-sided Culverts (CMS 706.051), or Precast Reinforced Concrete Arches (CMS 706.052) structures.
The following are trench specifications for new construction. Reconstruction plans may indicate other trench configurations.
In cuts, Structural Backfill Type 1 or 2 is required for 4 feet (1.2 m) above the top of the structure or to a height equal to the subgrade (whichever is less), and to a width equal to 2 feet (0.6 m) measured from the outside of the structure to the trench wall.
In a fill, Structural Backfill Type 1 or 2 is required for 2 feet (0.6m) above the top of the structure and for a width equal to 4 feet (1.2 m) measured from the outside of the structure to the trench wall.
In a cut or fill above the minimum heights specified soils and/or granular embankment may be used.
Trench conditions can change from location to location. The bottom and trench walls may change from rock to soft clay or silt. The compaction equipment used by the Contractor may change from the bedding to the backfill material. All backfill material lifts except Structural Backfill Type 3 are 8 inches (200mm) thick. Structural Backfill Type 3 is 12 inches (300mm) thick.
For soil embankment the density requirement is 96% of AASHTO T 99.
For soils that meet the requirements of CMS 603 the One-Point Proctor Method along with the Ohio Typical Density Curves can be used to establish the compaction requirements. The one point proctor and the moisture content of the proctor soil are used to find the curve that represents the tested soil. Once the curve is found, only 96% of the maximum dry density is required. The detailed procedures for compaction testing are explained in section for Supplement 1015.
Controlling the compaction of granular embankment by using the Test Section Method is superior over any other method. The Test Section Method allows for the adjustment of the density requirements to meet the material, compaction equipment, and the trench condition changes. When the trench bottom or the trench walls are too soft, the fixed density requirement may not be physically achievable. This may not be a result of Contractor negligence but a result of field conditions. It is difficult to obtain fixed density in soft foundation conditions. A test section is used to establish the compaction controls.
Compaction acceptance and procedures are detailed in Supplement 1015.
According to 603.06, when Type 2 Bedding is used, the middle 1/3 of the pipe bedding is left uncompacted (or lightly compacted to hold the grade of the pipe). If you divide the span or the diameter of the pipe into 3 parts; the bedding below the middle 1/3 of pipe is left uncompacted or lightly compacted.
Due to physical differences between Type 1, 2, and 3, the compaction controls are different. The Type 3 material (#57's or #67's) is not conducive to compaction testing; using a procedural method controls the compaction requirements.
There is no compaction testing requirements for the placement of the Type 3 material. The material is placed at a maximum lift thickness of 12 inches (300 mm). The material is then compacted to approximately 85% of the original lift thickness. The compaction should consist of vibratory plates, jumping jacks, or hand tamps. Although it may not seem like the compaction effort is accomplishing very much, it seats the material in place. To demonstrate the effectiveness of this compaction effort, fill a concrete mold with type 3 material and then weigh the filled mold. Then fill a second concrete mold using three equal lifts of type 3 material. Compact with a flat device after each lift is placed. Then weigh the second mold. The difference in weight will be about 20%. The same conditions exist in a pipe trench.
1. Concrete riprap
a. Size, spacing, depth, and clearance maintained on reinforcing steel
b. Concrete items of 499 apply
c. Joint width and depth and how filled if used
d. Amount of curing compound used
e. Dimensions of cutoff wall (length x width x depth)
f. Measure length and width for pay
2. Crushed aggregate slope protection
a. Measure depth of crushed aggregate placed
b. Measure length and width for pay
3. Concrete slope
a. Depth of concrete
b. Depth increased from 6 to 18 inches (15 to 46 cm) on last 3 feet (1 m) of bottom edge
c. Depth and spacing in both directions of joints
d. Amount of curing compound used
e. Measure length and width for pay
4. Dump Rock Fill
a. Stone placed conforms to Type________ (A, B, C or D, 703.19)
b. Measure length and width for pay
5. Rock Channel Protection
a. Stone placed conforms to type ______ (A, B, C or D, 703.19)
b. Large stone placed on a 6 inches (15 cm) bed of _______ (#3, #4 aggregate)
c. Measure length x width x depth for pay
d. Note type of filter used (if fabric), width of lap, and pin placement and length. If stone, note depth and material used.
6. Paved gutter
a. Make drawing showing section of gutter
b. Widths and depth of joint
c. Spacing on joints
d. Joint filler used
e. Amount of curing compound required and used
f. Base wet prior to placing concrete
g. Measure length for pay as per 601.12
1. Take adequate measures to keep concrete from freezing. State method used.
2. Blocks and brick wet before placing
3. Mortar composed of one part cement to two parts sand
4. Full mortar joints used
5. Method of cure
6. Measure length x width x depth for pay
7. Headwalls
a. Form dimensions - height to invert, total height, width, and thickness
b. Size and number, spacing and clearance maintained on reinforcing steel if required
c. Quantity for pay from standard
d. Method of cure
e. Backfill placed in loose lifts of 4 inches (10 cm) or less and tamped
8. Precast Headwalls & Wing walls
a. Must be pre-approved before use and produced by a certified precast concrete producer and shipped with a TE-24.
b. Measure length x width x depth for pay
c. Use non-shrink grout to fill void between conduit and wall
1. Document on form CA-P-1 or CA-P-3 as appropriate.
2. Must be produced by a certified precast concrete producer and shipped with a TE-24.
3. Measure length for pay (Note: Pay through or to the center of all junctions such as manholes, catch basins, etc. as per 603.14 of the CMS)
4. Document the following on the CA-P-1 Daily Pipe Inspection Form for each run of conduit.
a. List the equipment, number of passes, and lift thickness required for the bedding used
b. List the equipment, number of passes, and lift thickness required for the backfill used
c. List the type of the backfill material moisture density curve used if required
d. List all the compaction checks of the bedding
e. List all the compaction checks of the backfill
f. List how the haunch material is compacted
1. Use CA-P-1 Daily Pipe Inspection Form for each run of conduit.
2. Note how the site was restored (type of pavement replacement)
3. Note how the excavated material was taken care of (removed and disposed or used)
1. Use the CA-P-1 Daily Pipe Inspection Form for each run of conduit.
a. Note either existing or proposed pipe being field paved
b. Note height of cover placed before field paving
c. Note any repairs that were done before the field paving
d. Note type of reinforcement used
e. Note how reinforcement was attached to the pipe
f. Note the quantity of concrete furnished