Round Concrete Pipe

Engineered Integral Structure
Proven 100-Year Lifecycle

Reinforced concrete pipe is made by a machine the same way, time and again, in a controlled environment. RCP is a constant product, manufactured with certified materials according to ASTM C76 and ASTM C443 standards. Each reinforced concrete pipe is a high-strength structure, ensuring the majority of the design parameters are present post-installation. The RCP advantage is that when the product is delivered, it has already passed rigorous tests that ensure its durability over many decades. In that sense, it is already a structure when it is delivered, with a known outcome.

Design engineers want ease of design for every project. LRFD design tables are created based upon minimum allowable D-Load values in a positive projecting embankment condition per the AASHTO LRFD Bridge Design specifications at the surface. Proper class determination of RCP takes less than one minute using the design tables.

SDDOT Manning Score

The SDDOT independently load tests all pipe runs, confirming that RCP meets or exceeds ASTM C76 standards and specifications. Only pipe that meets ASTM C76 may ship. Results are posted regularly on the SDDOT Pipe Release web page.

Benefits of RCP

  • SDDOT Manning’s Value of .012, used in design, is present following installation
  • Structure delivered encompasses up to 90% of the soil-pipe structure
  • 100 year proven lifespan
  • 13 psi waterproof gasket
  • Affords contractor greatest margin for error
  • Lowest risk to design engineer
  • Lowest cost to owner

CASE STUDY: Harrisburg HDPE Pipe Installation – What Went Wrong?

This photo illustrates what goes wrong when flexible pipe is installed the same way that RCP is installed. This HDPE installation was not designed properly. It was incorrectly installed, and not inspected, leading to a variety of issues. In the field, flexible pipe requires much more preparation, inspection and post-installation testing, as well as extensive bedding materials and contractor attention to detail to avoid issues.
A.Flexible pipe relies on proper installation and properly compacted aggregate backfill to provide its structure in the soil/pipe envelope. This flexible pipe installation was “faster,” because it was installed as if it had the same structural properties as reinforced concrete pipe. Only a scant amount of sand backfill is visible in this installation – fine for RCP, but a big problem for flexible pipe.

B. Flexible connectors were not used. When the flexible material deflects or experiences thermal expansion and contraction, the void created between the flexible pipe and the rigid concrete structure will leak. RCP does not expand and contract.

C. Three feet of cover is required above the top of this pipe to support a 60,000-pound load. During surfacing operations, neither a ready-mix truck nor a loaded asphalt truck may pass over this pipe without violating the manufacturer’s guidelines and potentially damaging the installation.

D. When installed, this was a smooth wall pipe with no corrugations. The improper installation caused the pipe to corrugate, which disrupts the water flow and impacts performance.

This installed “smooth wall” flexible pipe actually possesses SDDOT corrugated wall Manning’s Value closer to .024, versus RCP installed value of .012. Furthermore, RCP is not subject to corrugation growth or thermal expansion and contraction.

What went wrong…

  1. Engineered design not created
  2. No inspection
  3. Improper backfill methods and compaction equipment
  4. Improper backfill materials and thicknesses
  5. Lack of flexible connectors
  6. Three feet of cover above the pipe, necessary for surfacing operations, is not present
  7. No post-installation testing performed with a 9-point mandrel or laser profiling
Plastic pipe installation Harrisburg Corrugation Growth