Section 4 — Structures and Foundations

Special Sewer Systems

IPE Engineering Practice IPE-EP-4-8-3

Document number: IPE-EP-4-8-3 · Section: 4 — Structures and Foundations

SCOPE

This Practice provides mandatory requirements for the design construction and installation of special sewer systems. The sewer systems described in this Practice apply where maximum environmental protection is required.
The special sewer systems covered by this Practice include aboveground sewers, closed sewer systems, and buried or below-ground sewers with double-walled components, or in lined trenches.
For general sewer systems not covered by this Practice, see EP 4-8-1.
Any deviation to this Practice must be approved by the procedures described in EP 1-1-3.
An asterisk (*) indicates that a decision or approval by the Owner's Engineer is required, or that additional information is furnished by the Purchaser.
A revision bar indicates all changes made to this Revision.
Documentation required for the construction of special sewer systems in accordance with this Practice is given in Table 3.

2.0 REFERENCES

The latest edition of the following standards and publications are referred to herein.

STANDARDS AND PUBLICATIONS

IPE Engineering Practices	IPE Engineering Practices
EP 1-1-3	Deviations to IPE Engineering Practices
EP 4-2-2	Earthwork
EP 4-2-10	Atmospheric Storage Tank Foundation Monitoring, Repair and Retrofit
EP 4-8-1	Sewer Systems
EP 4-8-2	Typical Sewer Details
EP 5-1-3	Piping Stress Analysis and Supports
EP 5-5-3	Piping Erection and Testing
EP 5-9-1	Design and Installation of Non-Metallic Piping
EP 5-9-2	Plastic-Lined Metallic Pipe
EP 5-9-3	Cement-Lined Metallic Pipe
EP 3-7-1	Pressure Relieving Systems
AASHTO	AASHTO
M245 Standard Specification for Corrugated Steel Pipe, Polymer Precoated Sewer and Drains	M245 Standard Specification for Corrugated Steel Pipe, Polymer Precoated Sewer and Drains

STANDARDS AND PUBLICATIONS (CONT.)

ANSI/AWWA
C105/A21.5 Polyethylene Encasement for Ductile Iron Piping for Water and Other Liquids C110/A21.10 Ductile Iron and Gray Iron Fittings, 3 in. through 48 in., for Water and Other Liquids C111/A21.11 Rubber Gasket Joints for Ductile-Iron and Gray-Iron and Pressure Pipe and Fittings C151/A21.51 Ductile Iron Pipe, Centrifugally Cast in Metal Molds or Sand-Lined Molds, for Water or Other Liquids
ASME
B31.3 Chemical Plant and Petroleum Refinery Piping
ASTM
A53 Pipe, Steel, Black and Hot-Dipped, Zinc Coated Welded and Seamless A74 Cast Iron Soil Pipe and Fittings A106 Seamless Carbon Steel Pipe for High Temperature Service A760 Corrugated Steel Pipe, Metallic Coated for Sewers and Drains A862 Application of Bituminous (Asphalt) Coatings for Corrugated Steel Sewer and Drainage Pipe A865 Threaded Couplings, Steel, Black and Hot-Dipped, Zinc-Coated (Galvanized) C76 Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe C425 Compression Joints for Vitrified Clay Pipe and Fittings C443 Joints for Circular Concrete Sewer and Culvert Pipe, Using Rubber Gaskets C564 Rubber Gaskets for Cast Iron Soil Pipe and Fittings C700 Vitrified Clay Pipe, Extra Strength Standard Strength, and Perforated D1785 Poly (Vinyl Chloride) (PVC) Pipe Schedules 40, 80 and 120. C2665 Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste and Vent Pipe and Fittings D2949 3.25 In Outside Diameter Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste and Vent Pipe and Fittings D2996 Filament Wound Fiberglass (Glass-Fiber Reinforced Thermosetting Resin) Pipe D2997 Centrifugally Cast Reinforced Thermosetting Resin Pipe D4160 Reinforced Thermosetting Resin Pipe (RTRP) Fittings for Non-Pressure Applications D4161 "Fiberglass" Glass-Fiber Reinforced Thermosetting Resin Pipe Joints Using Flexible Elastomeric Seals

DEFINITIONS

Aboveground sewer system - Sewer system with the majority of piping installed above grade on pipe supports or in covered, lined trenches. Sumps and buried piping may be required immediately beneath process drains and surface drainage areas.

Catch basin - An open basin which collects stormwater runoff from Plant surfaces and Plant wastewater from process drains.
Closed sewer system - Sewer system maintained under positive or negative gage pressure, venting to an emissions control system.
Double-walled Sewer System - Sewer system whose components have a secondary wall or liner outside of the primary wall, to protect the subgrade from leaks and to provide an annulus for leak detection.
Fire seal - means of preventing the movement of a flame front in the vapor space of a partially filled pipeline, also referred to as water seal or fire stop.
Junction Box - A manhole or other access to a wastewater sewer line system.
Manhole - Cased hole which allows bodily access to a sewer system through a covered hatch on top.
Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a manufacturer by a contractor or the Owner. An indirect order is one issued to a manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
Owner - Inflection Point Engineering, LLC.
Owner's Engineer - A Inflection Point Engineering, LLC appointed engineer.

MATERIALS

Acceptable materials for sewer piping components and material standard references are given in Table 1 and Table 2, respectively.
In double-walled systems, both primary and secondary component wall materials shall be compatible with the full range of services that will drain into the sewer.
(*)Where pipe components of double-walled sewer systems are plastic, adhesive bonding may be permitted, provided the particular adhesive joint design has a successful service history in pipeline applications, and is compatible with all services that will drain into the sewers. In lieu of successful service experience, leak tests, strength tests and accelerated aging tests shall be performed by the Manufacturer to qualify an adhesive joint design. The Owner's Engineer shall specify the specific criteria for the evaluation of the design.

5.0 GENERAL DESIGN

Special sewer systems shall be designed in accordance with all applicable national and local environmental and construction codes and regulations. Where requirements in this Practice conflict with those in national and local codes and regulations, the more stringent requirements shall apply.
(*)Drawings and specifications required for the design shall be submitted to the Owner's Engineer.

(*)Unless otherwise specified by the Owner, a sewer system shall be designed in accordance with EP 4-8-1 when codes and regulations do not require design to the more stringent requirements given in this Practice.
For gravity flow design, sewer components shall be sized in accordance with the requirements of EP 4-8-1. Applicable flows for gravity design are given in Section 5.0 of EP 4-8-1.
Surface drainage and drain sizing and location shall be in accordance with EP 4-8-1.
Sewer pipeline joints shall be welded, mechanical jointed or flanged.
Design for non-metallic pipe components shall be in accordance with EP 5-9-1. Design of plastic lined and cement lined metallic pipe shall be in accordance with EP 5-9-2 and EP 5-9- 3, respectively.
Thrust blocks shall be designed in accordance with EP 5-1-3.

DOUBLE-WALLED AND BELOW-GRADE, TRENCHED SEWER SYSTEMS

Piping Components
The pipe segment within a process slab shall be double-walled, see EP 4-8-2 for typical details.
All piping beyond the drain, terminating in manholes, junction boxes, catch basins, or other equipment or appurtenances shall be double-walled, see EP 4-8-2 for typical pipe component details.
(*)For double-walled piping component designs not found in details given in EP 4-8-2, service history and design data shall be submitted by the Manufacturer to the Owner's Engineer for review and design approval.
Trenches for below grade sewers shall be made of Portland cement concrete or polymer concrete.
Membrane liners shall be installed in trenches for below-grade sewers and shall comply with the requirements of EP 4-2-10.
Piping in trenches shall be supported off the trench bottom.
Trenches shall be provided with sealed covers. All segments of covers shall be removable.
Leak Detection and Other Controls
Double-walled and below-grade trenched sewers shall have leak detection systems.
(*)Leak detection in double-walled and below-grade, trenched sewers shall consist of one or more of the following systems, unless otherwise approved by the Owner's Engineer.
Monitoring of vapors in the annulus between the two walls
Monitoring of fluids in the annulus between the two walls using electrical cabling
Visual monitoring at inspection wells or beneath removable covers.
Positive or negative pressure loss in the annulus between the two pipe walls
(*)Leak detection system service history and design data shall be submitted by the Manufacturer to the Owner's Engineer for review and design approval.

Monitoring wells, if used as a means of leak detection shall be spaced to allow monitoring at each manhole, junction box, catch basin and clean-out.
(*)Other controls, including but not limited to, flammable vapor detectors, flow indicators, and pressure transducers, shall be specified and approved by the Owner's Engineer.
Appurtenances
Manholes, catch basins, junction boxes, fire seals, vents and cleanouts shall be designed, sized and located in accordance with EP 4-8-1, except all buried components shall be double-walled and shall have leak detection in accordance with this Section, see EP 4-8-2 for typical details.
For double-walled manhole, catch basin, junction box, fire seal, vent and cleanout designs not found in details given in EP 4-8-2, service history and design data shall be submitted by the Manufacturer to the Owner's Engineer for review and design approval.

ABOVEGROUND SEWER SYSTEMS

Piping Components
All buried pipe segments of an aboveground sewer shall be double-walled or in concrete vaults, see EP 4-8-2 for a typical detail.
Aboveground pipe segments shall be supported on pipe racks. Piping supports shall be designed in accordance with EP 5-1-3.
Piping on Racks
Aboveground sewer piping may be supported on existing racks provided analyses demonstrate the supports are capable of carrying the additional load.
(*)Piping on racks shall be provided with protection from adjacent hot services, when necessary. These lines shall pass over concrete on grade, unless other subgrade protection is approved by the Owner's Engineer.
Leak Detection and Other Controls
Leak detection in aboveground sewers shall be visual. The frequency of visual inspection will depend on the nature of the materials being conveyed, and shall be based on the requirements of regulatory agencies.
Buried components of aboveground sewers shall be provided with leak detection in accordance with this Practice.
(*)Other controls, including but not limited to, flammable vapor detectors, flow indicators, and pressure transducers, shall be specified by the Owner's Engineer.
Appurtenances
Catch basins, junction boxes, fire seal, vents and cleanouts shall be designed, sized and located in accordance with EP 4-8-1.
Sump and lift station pumps shall be designed for the flows given in EP 4-8-1. Spare pumps with auto-start capability shall be provided at all sumps and lift stations. Spares shall be the same size as the main pump.
(*)Sump and lift station location shall be specified by the Owner's Engineer.

Sump and lift station containment areas shall be sized to provide a minimum of five minutes of temporary storage based on the greater of the 25-year rainfall intensity or firewater requirements. Normal process sewer flows shall be taken into consideration if the sewer system is not segregated.

CLOSED SEWER SYSTEMS

Piping Components
Design of closed, pressurized sewer pipe components shall be in accordance with ASME B31.3 and this Practice.
(*)When specified by the Owner's Engineer, buried piping components of closed sewers shall be double-walled, see EP 4-8-2 for typical details. If double-walled construction is specified, closed sewer piping components shall also comply with the requirements of Section 6.0.
(*)Only carbon steel and ductile iron piping components shall be used in closed sewers, unless otherwise specified and approved by the Owner's Engineer.
Controls
Closed sewers shall be provided with pressure relieving systems to protect piping and associated equipment. The pressure relieving systems designed to protect storage tanks, vessels and other equipment in-line with, but not apart of, the sewer shall not be used to protect connected sewer components.
Pressure relieving systems shall be designed in accordance with EP 3-7-1. In a process sewer system, a minimum of one pressure relief device shall be required in each process unit area served by the sewer.
(*)Other controls, including but not limited to, flammable vapor detectors, flow indicators, and pressure transducers, shall be specified by the Owner's Engineer.
Appurtenances
Manholes, catch basins, junction boxes, fire seals, vents and cleanouts shall be designed, sized and located in accordance with EP 4-8-1. If double-walled construction is specified, design of appurtenances shall also comply with the requirements of Section 6.0.
(*)Nitrogen blanketing system designs or other purge system designs shall be submitted to the Owner's Engineer for approval.

9.0 INSTALLATION

Where applicable, sewer pipelines shall be installed in accordance with the references in Table 6 of EP 4-8-1.
Excavation for aboveground sewer pipe in trenches shall be in accordance with EP 4-2-2.
Aboveground sewer pipe shall be installed in accordance with the requirements of EP 5-5-3.

10.0 TESTING

(*)Atmospheric pressure sewers shall be tested in accordance with the requirements of EP 4- 8-1. Results of sewer tests shall be submitted to the Owner's Engineer.

Pressurized sewers shall be tested in accordance with the requirements of EP 5-5-3, except that the minimum test pressure shall be 25 psig.
All seams of membrane liners used in trenches shall be leak tested and strength tested in accordance with EP 4-2-10.

11.0 FLUSHING

All sewers shall be flushed, drained and cleaned after testing in accordance with the requirements of EP 4-8-1 and EP 5-5-3.

12.0 TABLES

TABLE 1

PIPE SELECTION GUIDE

Service	Service	Type of Pipe
Process wastewater		Carbon steel pipe
Process wastewater	Non-corrosive	Cast iron soil pipe
Process wastewater	Non-corrosive	Ductile iron pipe
Process wastewater	Non-corrosive	Reinforced concrete pipe
Process wastewater	Corrosive	Vitrified clay pipe
Process wastewater	Corrosive	Plastic Pipe
Process wastewater	Corrosive	Any of the pipes listed for non-corrosive service if suitably lined
Process wastewater	Corrosive	Lined fiberglass reinforced plastic
Stormwater sewer	Stormwater sewer	Reinforced concrete pipe
Stormwater sewer	Stormwater sewer	Cast iron soil pipe
Stormwater sewer	Stormwater sewer	Ductile iron pipe
Stormwater sewer	Stormwater sewer	Plastic Pipe
Sanitary sewer	Non-corrosive Gravity	PVC Pipe
Sanitary sewer	Non-corrosive Gravity	Cast iron soil pipe
Sanitary sewer	Non-corrosive Gravity	Reinforced concrete pipe
Sanitary sewer	Force main	Ductile iron pipe
Sanitary sewer	Corrosive (labs)	Mechanical joint flame retardant, polypropylene
Sanitary sewer	Corrosive (labs)	Lined fiberglass reinforced pipe
Floor drain	Floor drain	Cast iron soil pipe
Floor drain	Floor drain	Ductile iron pipe
Floor drain	Floor drain
Culvert	Culvert	Corrugated metal pipe with bituminous or polymer coating
Culvert	Culvert	Reinforced concrete pipe
Vent piping	Vent piping	Galvanized steel SCH 40

TABLE 2

PIPE MATERIAL STANDARDS REFERENCES

Type of Pipe	Applicable Standards	Applicable Standards
Cast iron soil pipe	ASTM ASTM	A74 C564
Ductile iron pipe	ANSI/AWWA ANSI/AWWA ANSI/AWWA ANSI/AWWA	C151/A21.51 C110/A21.10 C111/A21.11 C105/A21 .5
Reinforced concrete pipe	ASTM ASTM	C76 C443
Vitrified clay pipe	ANSI/ASTM ANSI/ASTM	C700 C425
Fiberglass reinforced plastic pipe	ASTM ASTM ASTM ASTM	D4160 D4161 D2996 D2997
Corrugated metal pipe	ASTM ASTM AASHTO	A760 A862 M245
Carbon steel and Galvanized pipe	ASTM ASTM ASTM	A53 Grade B A106 A865
PVC PIPE	ASTM ASTM ASTM	D1785 D2665 D2949

NOTE:

Other Plastic pipe materials and material standard references are given in EP 5-9-1.

TABLE 3

DOCUMENTATION REQUIREMENTNS FOR SPECIAL SEWERS PER EP 4-8-3

Item	Description	Format	As-Built
1	Drawings and specifications.	See EP 2-5-2	Yes
2	Design data and service history for alternative double-walled designs.	Text	N/A
3	Design data and service history for leak detection systems.	Text	N/A
4	Design data and service history for alternative appurtenance designs.	Text	N/A
5	Results of sewer testing.	Text	N/A

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