Stormwater management products FREQUENTLY ASKED QUESTIONS

What are Stormwater Management products?
Stormwater management products are structures designed for underground installation that have been specifically engineered for the treatment and removal of pollutants from stormwater run-off.
These precast concrete products include vaults, catch basins and manholes. Most stormwater management products are modular in design and are available in a number of configurations. The structures and all connections are constructed with watertight integrity so that the contents discharge only through the proper outlet and at a prescribed flow.

What is the difference between stormwater retention and detention?
Detention is the short-term storage of stormwater. The objective of a stormwater detention structure is to regulate or control the runoff or discharge rates from rainfall to reduce harmful effects of surge on downstream structures or systems.
Retention is the permanent storing of stormwater.

What are the advantages of precast concrete stormwater structures over alternative materials and construction methods?
Precast concrete structures offer the stormwater management industry distinct advantages in design, manufacturing, installation and maintenance:

• DESIGN:
  Engineered Structural Products
  Precast concrete structures are built according to rigid standards adopted by nationally accredited organizations such as ASTM and ACI. The structural integrity of the product makes it capable of supporting heavy loads on its own merits with varying degrees of cover, and its load-carrying capacity is less dependent upon a supporting envelope of material.

Footprint Efficiency
The modular capabilities of precast concrete components allow the optimization of space to achieve the treatment criteria on any given site.

Flexibility
There is no limit to what can be created with precast concrete. Customization to accommodate unique shapes, sizes and storage requirements can be easily accommodated within the standard operations of a precast concrete facility.

Durability
Precast concrete is one of the oldest proven building materials in the world. Precast products are capable of outlasting the storm event cycles for which they are designed.

• MANUFACTURING:
  Controlled Environment
  Because precast is manufactured in a climate controlled setting, the variables of temperature, humidity and inconsistencies in materials common to onsite operations are eliminated, producing a high degree of quality and uniformity.

Quality Control
Consistent quality control procedures create a checks and balances system that tracks monitors the quality of the manufacturing process – from the fabrication of reinforcing materials to the job site delivery of the product.

 

• INSTALLATION:
  Speed and Ease
  The modular nature and simple joint connections of precast concrete components enable rapid assembly onsite. Once in place, precast components are not subject to the misalignment possible with lighter weight materials. Less backfilling is also required, so once the units are in place the crew is off to the next location in significantly less time than with alternative materials.

Safety
Smaller excavations are required for precast concrete installations, reducing the exposure to cave-ins for the crew.

Resistance to Buoyancy
Precast concrete resists the buoyant forces of water. Because of its weight and strength, it can be placed in an excavation much easier than lightweight materials.

 

• MAINTENANCE:
  Safety
  The structural integrity of precast concrete provides a more stable work environment for the ongoing maintenance operations of stormwater management products.

Ease of Access
Typical standard manhole access arrangements and larger individual components make precast concrete stormwater management structures readily accessible without requiring work in cramped quarters or special equipment for hard to reach spaces.

Do precast concrete manufacturers have internal quality control programs?
All reputable precast concrete manufacturers have internal quality control programs.
Individual programs typically consist of a plant-specific Quality Control Manual, documents and forms for testing, inspection, work instructions, procedures and records. Internal quality control programs provide documentation of the process and offer records indicating compliance to the requirements.

What is the NPCA Plant Certification Program?
The Plant Certification Program sponsored by the National Precast Concrete Association is dedicated to setting standards of production, operations and quality control procedures that result in the manufacturing of consistent, high quality products. NPCA Plant Certification assures quality-conscious architects, engineers and end users of superior workmanship from pre-qualified precast concrete manufacturers.
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How can I find a producer of precast stormwater management products in my area?
Visit the NPCA online member directory, where you can search for a particular product and refine your search by company, state and certified plant. Or contact NPCA.

How can I find a company that supplies accessory products for precast concrete stormwater management structures?
Visit the NPCA online supplier directory, where you can search for accessories by keyword. Or contact NPCA..

What industry standards and specifications address precast concrete stormwater products?
Work is currently progressing in a newly created subcommittee of ASTM. The new subcommittee is C27.70 on Precast Concrete Products for Stormwater Management. The subcommittee will address the formulation of test methods, specifications, definitions, recommended practices and the promotion of knowledge relating to the application and performance of precast concrete products used for stormwater management in their scope.