Concrete Thinking Think Concrete
SOLUTIONS APPLICATIONS RESOURCES CASE STUDIES THINKERS
www.ConcreteThinker.com
Applications  > Water Infrastructure
Store, move, and treat water
Print   eMail
   
 
Concrete plays a major role in providing infrastructure for storing, conveying, treating and protecting water supplies. Concrete is used extensively in new construction and to repair existing infrastructure.

Types of concrete-based products used for these purposes include conventional concrete, roller-compacted concrete (RCC), soil-cement or flowable fill, grouts, and precast blocks.
uses

 

water infrastructure repairWater conveyance:
 
    • concrete pipes,
    • tunnels and
    • culverts.
Storage:
 
    • cisterns and
    • tanks.
Other applications include:
 
    • water and wastewater treatment facilities
    • dams
    • spillways
    • canals
    • bank protection
    • reservoir liners
why
Concrete needs no special treatments or coatings to allow it to hold water or wastewater. Concrete storage tanks, pipes, and tunnels provide these characteristics:

Inert material. Concrete contains water without imparting any unwanted flavor to it.

Meets health standards: Concrete does not leach toxic materials, whether incorporated in the concrete, or carried through it as waste effluent. Cementitious materials are tested and certified for use in concrete products in contact with drinking water. The extensive test program is performed on standard drinking water exposed to cement products; results are compared to the U.S. EPA National Primary Drinking Water Standards, ensuring that certified cements do not contribute to potential adverse human health effects. Nearly all U.S. states have adopted the voluntary standard - ANSI/NSF61 Drinking Water System Components – Health Effects. {More on leachability testing}

Long life and low maintenance: Historical data show that specifiers and users can expect a product life of 100 years or more for concrete pipe. Concrete pipes and tanks are virtually maintenance-free, an attribute essential for structures built underground or those that cannot be easily shut down for maintenance. Concrete does not experience significant creep or stress relaxation as it ages, thereby minimizing deflection and increasing service life. Concrete does not burn or support combustion. It does not degrade under exposure to ultraviolet light or extreme temperatures.

Corrosion, chemical, and acid resistant: Properly designed concrete resists corrosion caused by highly aggressive contaminants in wastewater as well as the chemicals added to treat these waste products. It is not vulnerable to attack from chemicals such as strong oxidizing acids, oils, alcohols, and polar reagents such as detergents. To counter the effects of acids in soil, precast concrete pipe can be produced with high-alkalinity concrete, increased concrete cover over reinforcement, a barrier coating or lining, or any combination of these. Design options exist to combat aggressive conditions and extend the service life of concrete pipe.

Aesthetics: Many municipalities require that large tanks be built below grade, and then cover them with a park or athletic facility to increase attractiveness. Because of concrete’s ability to perform well over time below-grade, and because of its structural characteristics, it can readily meet this requirement.

Range of Pipe Sizes and Ease of Installation: Concrete pipes range in size from 12 in. to 22 feet in diameter. Maximum pipe diameter is limited only by the restrictions of transporting them to the jobsite. Concrete pipe is not installation-sensitive. There is greater margin for error with concrete pipe than with other materials.

 

A relatively impermeable concrete can be achieved by specifying a low water-to-cement ratio for concrete. Small water-containment structures are often reinforced with conventional steel reinforcing bars. Larger tanks are reinforced with pre-stressed steel to increase their durability. In post-tensioning (a type of pre-stressing), contractors tighten high-strength steel strands embedded in the concrete walls of the tanks from either end after the concrete has hardened. This forces the concrete into compression and minimizes the likelihood of concrete cracking and subsequent water leakage. It also allows underground water or sewage-storage tanks to withstand pressure from inside and outside the tank.

Concrete pressure pipes, including municipal water mains, powerplant cooling water lines, and sewer force mains that carry liquids under pressure, are also reinforced with pre-stressing steel strands.

Sustainability

 

In addition to the general benefits of concrete construction (see cast-in-place and precast) concrete can play a role in sustainable building systems such as water storage for rainwater harvesting or greywater systems.
considerations

Shape: Circular concrete pipe is most commonly used, since it is hydraulically and structurally efficient under varied conditions. But circular pipe can cause reduction in stream width during periods of low flow. Elliptical concrete pipe is often used instead of circular pipe when the distance from the top of the pipe to ground surface is limited, or when a wider cross-section is desirable for low-flow levels. Rectangular cross-section box culverts fit into many site conditions, including those requiring low-profile structures.

Special Requirements: Specially designed precast concrete storm systems treat stormwater by separating hydrocarbon-laced silt, other liquids, sand, and debris from location runoff. Rain event removal rates of more than 80% are typical. Precast concrete filter chambers constitute a superior, below-ground fluid absorption system for cleaning septic tank effluent.

BOOKMARK
Resources
 Show Detail
Located at BookstoreConcrete Pipe Design Manual (2004)
American Concrete Pipe Association, #01-101, 330 pages
Available for $45 member, $22.50 non-member. An indispensable tool to help engineers select the type, size, and strength requirements of pipe. It eliminates the lengthy computations previously required. The manual includes standard installations using the indirect design method. More than 330 pages of tables and figures covering hydraulics of sewers and culverts, live loads and earth loads, supporting strengths and supplemental design data are listed. Detailed example problems of specific applications illustrate the use of the time saving design aids included in the manual.
Download DocumentNo Pipe Dream: Concrete Serves Water Users Best (2000)
Environmental Council of Concrete Organizations, #EV23, 4 pages
Available for free. Manufactured for endurance. Concrete pipe is the recognized leader in service life among buried pipe products. This four-page bulletin describes why water users are best served by concrete transmission and distribution systems.