SANITARY SEWERS

Sanitary sewers are conduits that carry liquid and water-carried wastes from homes, commercial facilities, industrial plants and institutions to a treatment plant for the express purpose of protecting our environment, safeguarding health, and improving our comforts and quality of life.

Concrete pipe is the most widely used and accepted permanent product of all sanitary sewer materials. It makes up the greater portion of the sanitary sewer system in most major cities in the United States. Sanitary sewers require that pipe meet infiltration limits, meet the strength conditions of any depth of backfill and superimposed load, and provide resistance to the effects of sewage.

Recommended Standard Specification

1. Scope

1.1 – This specification covers reinforced concrete pipe intended to be used for the conveyance of waste water.

2. Referenced Documents

2.1 ASTM Standards:

C 76     Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe
C 361   Reinforced Concrete Low-Head Pressure Pipe
C 443   Joints for Circular Concrete Sewer and Culvert Pipe, Using Rubber Gaskets
C 655   Reinforced Concrete D-Load Culvert, Storm Drain, and Sewer Pipe
C 822   Definitions of Concrete Pipe and Related Products
C 969   Infiltration and Exfiltration Acceptance Testing
C 1103 Joint Acceptance Testing of Installed Pre-cast Concrete Pipe Sewer Lines

3. Terminology

3.1 Definitions – For definitions of terms relating to concrete pipe, see Definitions C 822.

4. Materials

4.1   Reinforced Concrete Pipe – Reinforced concrete pipe shall be manufactured in accordance with ASTM C 76 or ASTM C 655. The manufacturer of the reinforced concrete pipe shall be on the Illinois Department of Transportation’s “List of Certified Plants.”
4.2   Pipe Class – The class of pipe shall be as shown on the plans.
4.3   Lift Holes – Lift holes shall not be permitted.
4.4   Joints – Joints shall conform to ASTM C 443 or C 361.
4.5   Gaskets – The gaskets shall be installed in accordance with the manufacturer’s recommendations. Prior to commencing installation, the contractor shall submit to the engineer:

4.5.1 – Manufacturer’s literature on the type of gasket to be used.
4.5.2 – Manufacturer’s literature on the type of lubricant to be used.
4.5.3 – Manufacturer’s recommended installation procedures, including equalization techniques.

4.6 Fittings – Fittings shall conform to the strength and water tightness requirements placed upon mainline pipe.

5. Excavation

5.1 Trench Depth – The trench shall be excavated to a firm foundation at least 4 inches below the bottom of the pipe so that the flow line of the finished sewer will be at the depth and grade specified by the engineer.

5.2 Trench Width – For trench depths of less than 5 ft. and when sheeting or shoring is not required, the trench shall be excavated 18 inches wider than the external diameter of the pipe. For trench depths of 5 ft. or more and when sheeting or shoring is required, the trench width shall be 3 ft. wider than the external diameter of the pipe.

6. Bedding

6.1 – Bedding material (pea gravel, crushed stone or washed gravel with at least 95% passing the 1″ sieve) shall be placed at least 4″ thick on the bottom of the trench. If any unyielding foundation is encountered, the minimum thickness shall be increased to 8 inches.

7. Installation

7.1 Handling – The contractor shall handle the pipe with care and avoid chipping or cracking the pipe.

7.2 Laying Pipe – The contractor shall keep the trench free from water during installation. The laying of pipe shall proceed upgrade, with spigot or tongue ends pointing in the direction of flow. The ends of the pipe shall be carefully cleaned before they are lowered into the trench. Each pipe shall be carefully aligned horizontally and vertically with the previous pipe and the joint pulled home. Care shall be taken to assure the gasket remains in its intended position.

8. Backfilling

8.1 Haunch – As soon as possible the entire width of the trench shall be backfilled with pea gravel, crushed stone or washed gravel (with at least 95% passing the 1″ sieve) to the pipe springline. Special care shall be taken to completely fill the space under the pipe. A flowable backfill mixture, described as controlled low strength material (CLSM), may be used.

8.2 Backfill – The remainder of the trench shall be backfilled to the natural grade or finished surface. This material may consist of material excavated from the trench. Care shall be taken to avoid disturbing the pipe.

8.3 Special Considerations – In areas where the trench will be under pavements, curbs, shoulders, sidewalks or other structures, granular material will be used to fill the entire trench. The granular material will be placed and compacted to the satisfaction of the engineer. A flowable CLSM may be used when high relative densities are desired.

9. Acceptance Testing

9.1 Types of Testing – Testing for acceptance of reinforced concrete pipe shall be conducted by one of the following methods:

9.1.1 – Water exfiltration, ASTM C 969
9.1.2 – Water infiltration, ASTM C 969
9.1.3 – Joint testing, ASTM C 1103

9.2 Test Sections – Unless otherwise specified or directed by the engineer, the first 1200 feet (or the entire length if the project is less than 1200 feet) shall be tested before additional excavation is permitted. If the initial section does not pass, it shall be repaired and retested until a satisfactory result is obtained. Excavation shall not proceed beyond the first 1200-foot section until satisfactory results are obtained.

In the event the first 1200-foot section did not pass the test on the first trial, the next section of sanitary sewer approximately 1200 feet long shall also be tested, repaired if necessary, and restored until a satisfactory result is obtained. Additional excavation shall not be started until this section has passed.

When favorable test results are obtained on the first trial for a full 1200-foot section, the engineer may designate additional sections for testing. The engineer reserves the right to select the location and lengths of additional test sections. All testing will be performed within 30 days of backfilling.

9.3 Water Exfiltration – The test shall be conducted in accordance with ASTM C 969.
9.4 Water Infiltration – The test shall be conducted in accordance with ASTM C 969.
9.5 Joint Acceptance Testing – The test shall be conducted in accordance with ASTM C 1103

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Applicable Specifications and Recommended Use

STORM SEWERS & CULVERTS

Applicable Specifications and Recommended Use

CIRCULAR PIPE

ASTM C 14 Concrete Sewer, Storm Drain and Culvert Pipe (Non-Reinforced)

C 14 pipe is to be used for the 8 in. and 10 in. diameter sizes,. It may be used for sizes 12 in. trough 36 in. diameter with the provision that C 76 pipe of comparable strength also be specified.  Joint provided for most storm sewer construction employ cement mortar or mastic compound.   For installations with internal or external head condition, joints may be provided meeting the requirements of ASTM C 443 utilizing a rubber gasket.

ASTM C 76 Reinforced Concrete Culvert, Storm Drain and Sewer Pipe

C 76 pipe is used for sizes 12 in. through 144 in. diameter and is available with bell and spigot or tongue and groove ends utilizing cement mortar or mastic compound joints.  These joints are adequate for most culvert and drainage installations.  For the special condition of internal or external heads, joints may be provided meeting the requirements of ASTM C 443 or ASTM C361 utilizing a rubber gasket. ASTM C 76 pipe is the most commonly used storm sewer pipe because of its excellent hydraulic capacity, resistance to abrasion and combustion, capabilities in meeting any variety of load conditions, and availability with a number of related appurtenances.

ASTM C 655 Reinforced Concrete D-Load Culvert, Storm Drain, and Sewer Pipe

C 655 pipe is used for sizes 12 in. through 144 in. diameters designed for specific D-load strength.  Joints provided for most culvert and drainage employ cement mortar or mastic compound.  The properties of the pipe are similar to ASTM C 76 pipe except that the pipe may be designed for a specific D-load strength and the design accepted on the basis of a statistical analysis of test specimens.

Special Shape Pipe and Precast Concrete Boxes

ASTM C 506 Reinforced Concrete Arch Culvert, Storm Drain, and Sewer Pipe

C 506 arch pipe is to be used for size  18 in. through 132 in. equivalent circular sizes and is available with tongue and groove cement mortar or mastic compound joint.  This arch shaped pipe is used for minimum cover situations or other conditions where vertical clearance problems are encountered.  IT offers the hydraulic advantage of greater capacity for the same depth flow than most other structures or equivalent water-way area.  Loads under similar cover conditions are similar to that of circular pipe with the same span.  If arch pipe is not available in a certain area, elliptical pipe may be substituted as an equivalent.

ASTM C 507 Reinforced Concrete Elliptical Culvert, Storm Drain, and Sewer Pipe

C 507 horizontal elliptical pipe is used for sizes 18 in. through 144 in.equivalent circular sizes with tongue and groove cement mortar or mastic compound joint.  The horizontal elliptical pipe is installed with the major axis horizontal and is used for minimum cover situations or other conditions where vertical clearance problems are encountered.  It offers the hydraulic advantage of greater capacity for the same depth of flow than most other structures of equivalent water-way area. Loads under similar cover conditions are similar to that of circular pipe with the same span.

C 507 vertical elliptical pipe is used for sizes 36 in. through 144 in. equivalent circular sizes with tongue and groove cement mortar or mastic compound joint.  The vertical elliptical pipe is installed with the major axis vertical and is used where minimum horizontal clearances are encountered or where unusual strength characteristics are desired.  Hydraulically, it provides higher flushing velocities under minimum flow conditions and carries equal flow at a greater depth than equivalent horizontal elliptical, arch, or circular pipe.   Loads under similar cover conditions are similar to that of circular pipe with the same span. Special installation techniques are required for vertical elliptical pipe.

ASTM C 789 Precast Reinforced Concrete Box Sections for Culverts, Storm Drains, and Sewers

C 789 box sections are used in sizes of span and rise from 3ft. by 2 ft. to 12 ft. by 12 ft. for earth covers over 2 ft.   Although not specifically called out by ASTM C 789, 2 ft. by 2 ft. box sections are also locally available.  Joints provided utilize tongue and groove type ends with cement mortar or mastic compound joints.  Box sections are used where special hydraulic requirements or cross sectional shapes are encountered (such as limited head room).  They offer the advantage of precast products over cast-in-place construction through low installation costs and minimum inconvenience of weather and traffic delay.   Box units may be used in parallel for multicell installations.

ASTM C 850 Precast Reinforced Concrete Box Sections for Culverts, Storm Drains, and Sewers with Less than 2 ft. (0.6 m) of Cover Subjected to Highway Loading

C 850 box sections are used in sizes of span and rise from 3ft. by 2 ft. to 12 ft. by 12 ft. with less than 2 ft. of cover. Although not specifically called out by ASTM C 850, 2 ft. by 2 ft. box sections are also locally available.  Joints provided utilize tongue and groove type ends with cement mortar or mastic compound joints.  Box sections are used where special hydraulic requirements and minimum cover are encountered.  They offer the advantage of precast products over cast-in-place construction through low installation costs and minimum inconvenience of weather and traffic delay.  Box units may be used in parallel for multicell installations.

The following tables are provided from the Illinois Department of Transportation’s “Standard Specifications for Road and Bridge Construction”, January 1, 1997 edition.  Please note that all applicable IDOT provisions must be adhered to when using these tables.  These tables were developed assuming a trench condition, and shall not be used for embankment conditions.

  • Storm Sewers (English)
  • Storm Sewers (Metric)
  • Culverts (English)
  • Culverts (Metric)
  • Elliptical & Arch Culverts (English)
  • Elliptical & Arch Culverts (Metric)

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