2503.01 DESCRIPTION.
This work shall consist of constructing sewers for removal of surface water from collection points adjacent to the road. The provisions of Section 2403 shall apply.

2503.02 MATERIALS.
The material used shall meet requirements of Division 41 for the respective items.

Pipe for storm sewers shall meet requirements of Article 4149.03.

All steel reinforcing bars used in intakes and utility accesses shall be ASTM A 615/A 615 M, Grade 60 (400).

2503.03 CONSTRUCTION.
The construction of storm sewers shall conform to the following requirements. If plastic pipe is specified, the requirements of ASTM D 2321 and the recommendations of the manufacturer shall also apply, unless otherwise noted in the contract documents.

A. Trench.
Trenches for storm sewers shall be of sufficient width to provide ample room for proper installation of the pipe and for placing and tamping backfill material under and around the pipe. When the contract documents require, or field conditions necessitate limitations on the top width of the trench resulting in the trench walls being cut vertically or sloping to a degree steeper than the natural angle of repose of the material being excavated, sheeting, shoring, and bracing shall be employed to the extent necessary to provide adequate safety to the workers engaged in the work. Sheeting, shoring, and bracing shall remain in place until backfilling has progressed to a stage that its removal will not result in damage to pipelines or other structures or injury to personnel. Trench widths greater than these must be approved by the Engineer.

The final bedding surface on which the pipe rests shall be firm earth or approved granular backfill material which is free of rocks, stones, roots, or other objectionable material greater than 3 inches (75 mm) in diameter. If the pipe can not be bedded in firm earth, excavation shall be carried below the required elevation as directed by the Engineer, then backfilled with granular material meeting requirements of Section 4120 or with sand containing not more than 10% passing the No. 200 sieve (75 µm sieve). The bedding shall be shaped as shown in the contract documents. If solid rock is encountered at the bedding elevation or within 6 inches (150 mm) below this elevation, excavation shall be carried 6 inches (150 mm) below the required elevation of the outside of the pipe, then backfilled with suitable material, well tamped, and the bottom of the trench shall be shaped as required for earth excavation.

For bell end sewer pipe, bell holes shall be excavated ahead of the placement of the pipe.

B. Laying and Placing Pipe.
Laying of pipes shall commence at the lowest point so the spigot or tongue ends point in the direction of flow. Proper methods shall be used for handling and placing pipe to avoid spalling or breaking and to avoid unnecessary disturbance of bedding surface in the trench bottom. Each pipe section shall be placed to line and grade and shall be carefully bedded and forced to a close end contact with the adjacent section.

If joints are open due to angles in alignment, the openings shall be covered with concrete collars. Collars shall be constructed of Class C concrete and shall have dimensions and reinforcement specified for Type C adapters shown in the contract documents.

C. Backfilling.
Backfill shall not be placed until the bedding, joints, line, and grade of the pipe have been approved by the Engineer. Backfill shall be suitable material free of boulders, frozen clods, roots, sod, or other vegetation. Backfill shall first be carefully hand tamped under and around the pipe in lifts not exceeding 4 inches (100 mm) in loose thickness to a height where a mechanical tamper can be used effectively. Care shall be used to so place and tamp this bedding course as not to disturb joints, alignment, or grade of the pipe. Filling shall be carried on simultaneously on both sides of the pipe.

Where the pipeline is placed beneath a roadway or driveway or within 5 feet (1.5 m) of the edge of an existing or proposed pavement or base course, tamping shall continue in 6 inch (150 mm) lifts to the surface, and such tamping shall be done with a mechanical tamper of an approved type or with a sheepsfoot roller if the width of the trench permits its use. In other cases, backfill shall be compacted by mechanical tampers to at least 6 inches (150 mm) above the top of the pipe. The balance of the backfill shall be consolidated by tamping or rolling in 6 inches (150 mm) layers.

Rock having dimensions not in excess of 15 inches (375 mm), removed as excavation during storm sewer operations, may be used for backfill material between planes 1 foot (0.3 m) above the top of the pipe and 1 foot (0.3 m) below subgrade elevation. Rock used as backfill shall be placed so as to prevent the formation of voids. Excess excavation shall be used or removed from the project as directed by the Engineer.

D. Intakes and Utility Access.
Intakes, and utility access shall be constructed in accordance with the contract documents. These items shall include forming walls and placing necessary pipe sections through the walls for inlet and outlet lines. All concrete in intakes or utility accesses shall be Class C concrete.

Precast concrete intakes and utility access units may be utilized and shall meet requirements of Article 4149.04.

If the unit is cast in place, the storm sewer pipe shall be installed before intake sidewall construction is started. Sidewalls shall be constructed with openings for storm sewer pipe(s) smoothly shaped and inlet pipe(s) not projecting into the well. Outlet pipe(s) shall not project beyond the inside face of the sidewall.

A concrete fillet shall be placed in the bottom of the intake approximately as shown in the contract documents. Special shaping of this fillet shall provide a smooth channel through the intake. The top surface of the fillet shall slope at a rate of approximately 12:1 toward the channel.

The insert area shall be included with the quantities for either concrete pavement or curb and gutter (only when curb and gutter is being added to existing pavement). Concrete for the insert area may be Class C or the approved paving mixture for the paving project. Finish on the insert area shall be the same as for the pavement. Finish of the intake top or any exposed portion shall be in accordance with Article 2403.21.

2503.04 METHOD OF MEASUREMENT.
The quantity of storm sewer pipe, in feet (meters), will be the quantity shown in the contract documents, for each storm sewer to the nearest foot (0.1 m). Such lengths shall exclude the space across intakes and utility access where pipe is not actually placed.

Type C adapters required by the contract documents or installed to correct faulty work will not be measured for payment. Type C adapters not shown in the contract documents, but required because of change in alignment, shall be paid for in accordance with Article 1109.03, B.

The quantity of aprons will be the quantity shown in the contract documents.

When granular material for backfill is required, Article 2402.12, D shall apply.

The quantity for each intake and utility access will be the quantity shown in the contract documents.

2503.05 BASIS OF PAYMENT.
The Contractor will be paid the contract unit price for storm sewer pipe of the type and size specified as follows:

A. When the contract documents indicate the elevations at which the storm sewer is to be constructed, and the pipes are laid as indicated in the contract documents or to a changed flow line not lower than 1 foot (0.3 m) below the elevations shown in the contract documents, the Contractor will be paid the contract unit price per linear foot (meter) of storm sewer completed.

If it becomes necessary to lower the flow line by more than 1 foot (0.3 m), payment for the overdepth excavation will be made as follows:

125% of the delivered cost of pipe per foot (meter) shall be deducted from the original contract unit price per foot (meter) of pipe. The remainder will be considered the contract unit price for excavation and laying of pipe. The contract unit price for excavation and laying of pipe shall be divided by the average depth from original ground profile of the total length of that particular size of pipe shown in the contract documents, and this quotient considered the basic excavation and laying price per foot (meter) of pipe, per foot (0.3 m) of depth. For depths of excavation more than 1 foot (0.3 m) below the specified bedding elevation, shown in the contract documents, payment for overdepth excavation will be made in accordance with the following schedule:

Overdepth Excavation*	Percentage of Basic Excavation and Laying Price
1st foot (0.3 m) 2nd foot (0.3 m) 3rd foot (0.3 m) 4th foot (0.3 m) 5th foot (0.3 m) 6th foot (0.3 m)	100% 120% 140% 160% 180% 200%
*For depth of excavation greater than 6 feet (1.8 m) below bedding elevation, specified in the contract documents, payment will be made as extra work, as provided in Article 1109.03, B. Bedding elevation refers to an elevation lower than the flowline in an amount equal to the wall thickness of the pipe being laid.

B. When the contract documents do not indicate the elevations at which storm sewer is to be constructed, the contract unit price per linear foot (meter) of storm sewer shall be full payment for that portion of storm sewer which has a depth to bedding elevation of 6 feet (1.8 m) or less below the original ground profile. For those portions of the storm sewer where depth to bedding elevation exceeds 6 feet (1.8 m), the overdepth excavation will be paid for as follows:

125% of the delivered cost of pipe per foot (meter) shall be deducted from the original contract unit price per foot (meter) of pipe. The remainder will be considered the contract unit price for excavation and laying of pipe for storm sewer of 6 feet (1.8 m) in depth. The contract unit price for excavation and laying of pipe, determined as provided above, will be divided by 6 and this quotient considered the basic excavation and laying price per foot (meter) of pipe, per foot (0.3 m) of depth.

For overdepth excavation required for the placement of storm sewer to bedding elevations greater than 6 feet (1.8 m), measured to the nearest foot (0.3 m) below the original ground profile over the trench, the rate of payment will be as shown in the following table:

Overdepth Excavation*	Percentage of Basic Excavation and Laying Price
1st foot (0.3 m) 2nd foot (0.3 m) 3rd foot (0.3 m) 4th foot (0.3 m) 5th foot (0.3 m) 6th foot (0.3 m)	100% 120% 140% 160% 180% 200%
*For depths of excavation greater than 12 feet (3.6 m) below original ground profile, payment will be made as extra work, as provided in Article 1109.03, B.

C. Under either condition outlined in Paragraph A or B above, if unexpected solid rock is encountered in the trench at any elevation, payment will be made for rock at four times the basic excavation and laying price per foot (meter) of pipe, per foot (0.3 m) of depth, for the thickness of rock encountered, and for the length over which it is encountered.

In those sections of the storm sewer lines where unexpected solid rock has been encountered, payment will be made for the length of storm sewer involved at the unit bid price as though no rock had been encountered, and additional payment will be made for the unexpected solid rock, based upon the length and depth at which it is encountered under the applicable conditions outlined in Paragraphs A and B above.

Existing pavement, boulders, and loose rock will not be measured as solid rock. When solid rock is encountered and the contract documents do not show evidence of its presence, the material will be considered unexpected solid rock.

When solid rock is encountered in the construction and the contract documents have indicated its presence in the general area of storm sewer construction, only that portion of rock encountered at elevations more than 2 feet (0.6 m) above the upper elevation of the rock, as indicated in the contract documents, will be considered unexpected. In determining the upper elevations of rock at intermediate points, within the area where actual elevations are not indicated, determinations will be made by interpolating between points of known or calculated elevations. If the calculated elevation of a given point determined on a straight line basis between two points of known elevation is in variance with the calculated elevation when computed between two other points of known elevation, the higher elevation calculated shall be used. Determinations of elevations by extrapolation will not extend more than 150 feet (45 m) outside the general area of known elevations.

D. The Contractor will be paid the contract unit price for each intake and utility access constructed and placed, for the type indicated, as shown in the contract documents. This payment shall be full compensation for satisfactory connection to new or existing storm sewer (connections to precast units shall be grouted); frames and covers (grates); and furnishing all materials and constructing the special shape insert area.

When the depth of flow line is increased by more than 1 foot (0.3 m), payment will be increased by the ratio of the actual depth to the intended depth, measured from the flow line of the gutter to the depth of flow line. If the plans do not indicate the depth to flow line, the intended depth will be assumed to be 6 feet (1.8 m). When the depth is increased by more than 6 feet (1.8 m), payment will be made as extra work.

Price adjustment will not be made because of class of excavation encountered in the excavation for intakes, or utility accesses.

E. Type C adapters shown in the contract documents or installed to correct faulty quality of work will be included in the cost per foot (meter) of pipe. Type C adapters required because of change in alignment will be paid for in accordance with Article 1109.03, B.

The Contractor will be paid the contract unit price for aprons of the type and size specified per unit.

F. When the contract provides for granular material for backfill, Article 2402.13, F shall apply. Granular material furnished according to Article 2503.03, A, will be paid for in accordance with Article 1109.03, B. The agreed price shall be the Contractor's unit delivered cost. Allowance will not be made for additional excavation or labor for placing granular material.