Clay Pipe Engineering Manual

Chapter 10, Residential Building Sewers

Lateral Sewers

A lateral sewer is a continuation of the municipal sanitary sewerage system. This installation demands the same special care and experience as municipal sewerage construction for the line to be permanent and trouble free. Installation should be performed by experienced and competent workmen.

Lateral sewers must be resistant to the action of corrosive chemicals. Ordinary sewage contains quantities of acetic, citric , sulfuric and lactic acid as well as organic acids. These sewers pass thou-sands of gallons of hot, soapy water, vegetable and fruit juices, a variety of cleansers and drain cleaners which are highly corrosive. In addition, the wide-spread use of garbage grinders introduces into sewers a large amount of organic matter. Dishwashers and wash-ing machines contribute large quantities of hot water which greatly increase the sewage temperature.

Lateral sewer pipe should not deflect, deform, soften, rust, decompose or disintegrate from the effect of domestic wastes, high sewerage temperatures, moisture saturation, sustained trench loading or cleaning equipment.

Trench Excavation

Pipe trenches should be dug with the same care required for main lines. Trenches should be straight and to the required slope, with width held to a minimum.

Where the soil is sufficiently firm to provide a solid foundation for the pipe, the trench bottom should provide uniform support for the barrel of the pipe. Bell or coupling holes should be dug at the proper intervals so that the weight is supported by the barrel of the pipe.

Care should be taken to excavate no deeper than necessary, unless there is a supply of angular crushed stone or other suitable coarse material available to bring the trench bottom to grade and provide uniform support for the barrel of the pipe. Rock or other unyielding material which is encountered should be removed. The pipe foundation should be free of all lumps and irregularities.

Where the bottom of the trench is either of rock, unyielding, or unstable material, it is advisable to excavate below grade and backfill to grade with angular crushed stone or similar material.

Installation

Each section of pipe should be laid to a specified line and grade. All pipe should be laid with bells or couplings upgrade.

As the installation progresses, the interior of the pipe should be cleared of all dirt and foreign material. The trench should be kept as dry as possible while the pipe is being laid. The specific manufacturers' recommendations should be carefully followed.

Backfilling

Normally the excavated earth is satisfactory for backfilling purposes. The trench should be backfilled as soon as inspection is completed. To protect the line from lateral movement, the backfill should be carefully placed around and to at least one foot above the top of the pipe.

NCPI Engineering Manual

Request a copy of the Clay Pipe Installation Manual or other publications from NCPI