www.concrete-pipe.org

ALL STORM PIPING PRODUCTS ARE NOT CREATED EQUAL!

Rigid Vs Flexible

Presentation by:

2

RCP VS Flexible Pipe SystemsHole is same but nothing else!

• IF YOU TAKE ANYTHING AWAY WITH YOU TODAY WE WANT YOU TO CLEARLY UNDERSTAND: RIGID PIPE IS DIFFERENT FROM FLEX.

PIPE Different in MANY WAYS:

• STUCTURAL STRENGTH • INSTALLATIONS • INSPECTION • POST INSTALLTION • SPECIFICATIONS AND DETAILS

3

Engineering Analysis:• Structural Strength• Installation• Inspection

Specifications and Std Details:• Materials, installation, inspection, structural verification

SAFETY & RISK Hydraulic common sense (1/2” corrugations = .010? No!) Risk of Pre-Mature Structural Failure (KY & OH HDPE

Issues) Flammability is REAL ISSUE

Economic Analysis:• REAL ECONOMICS

Consider Installation Cost Vs Lifetime Value

AGENDA

4

Definition of “Pipe”

Dictionary.com: “a hollow cylinder of metal, wood, or other material, used for the conveyance of water, gas, steam, petroleum, etc.

Webster’s On-Line: “a long tube or hollow body for conducting a liquid, gas, or finely divided solid or for structural purposes”

Oxford English Dictionary: “a tube used to convey water, gas, oil, etc.”

5

A Buried Pipe Must Perform Two Critical Functions?

Buried Pipe

Conduit/Hole

Structure

6

Concrete Pipe

Structure Conduit

RCP Provides Conduit + StructureRCP Provides Conduit + Structure

OTHER PIPES ????STRUCTURE?????

• Wall thickness for HDPE remains constant for all fill height or live loading conditions

• “Pipe” stiffness is time dependent and constantly decreases under load

• “Pipe” stiffness decrease for HDPE & CMP as pipe Dia gets larger!

• “Pipe” has little or no structural strength

Flexible Pipe

Conduit

Structure

?

?

?

? ?? ?

By Low Bidder

Flex. Pipe Wall = NO Strength to StructureFlex. Pipe Wall = NO Strength to Structure

9

60” ASTM C-76 Class III

D0.01 = 6,750 lb / lf

DULT = 10,000 lb / lf

Total Load Required for 8’ Pipe:

D0.01 = (8)(6,750)

= 54,000 lbs.

DULT = (8)(10,000)

= 80,000 lbs.

Understand what this means?

ASTM C-76 Class III RCP D0.01 = 1,350 lb / lf / ft (dia.) DULT =2,000 lb / lf / ft (dia.)

RCP – STRCTURAL CONFIRMATION!RCP – STRCTURAL CONFIRMATION!

Structure Confirmed before Shipment60” RCP is tested before it leaves

the point of manufacture to prove it can carry the load of a loaded Tractor and trailer with no lateral support!

THIS FACT AND PROVEN SERVICE LIFE Should give you CLEAR UNDERSTANDING OF DIFFERENCES OF RCP Vs FLEXIBLE

60” RCP is tested before it leaves the point of manufacture to prove it can carry the load of a loaded Tractor and trailer with no lateral support!

THIS FACT AND PROVEN SERVICE LIFE Should give you CLEAR UNDERSTANDING OF DIFFERENCES OF RCP Vs FLEXIBLE

LOAD INCREASES WITH PIPE DIAMETER

D

W w w w

TOTAL LOAD = 1 W

D-LOAD = LOAD

DIAMETER

TOTAL LOAD = 3 W

3D

The backfill or fill load increases in direct proportion to pipe diameter.

It is essential for pipe strength to increase with pipe diam. regardless of the pipe.

Is this thinking logical? Does this make sense?

Strength

02,0004,0006,0008,000

10,00012,00014,00016,00018,00020,000

12 15 18 24 30 36 42 48 54 60 72

Class 5

Class 4

Class 3

Class 2

1,350 lb / lf / ft (dia.)

2,700 lb / lf 5,400 lb / lf

Pipe Diameter

ASTM C-76 RCP Strengths

0.0

1” C

rack S

tren

gth

in

a 3

-E-B

RCP Increases Strength with Pipe Diameter to Carry Increased Load.

Pipe stiffness

HDPE PIPE CMP 24” 34 psi 224psi 36” 22 psi 62 psi 42” 19 psi 40 psi 48” 17 psi 27 psi

The Decrease in Pipe Strength Occurs at the Same Time the Load is Increasing.

What Should This Alert You To About Installation?

16 Gage

Structural Strength – HDPE & CMP

14

Corrugation Profiles

• 2 2/3” x 1/2”

• 3” x 1”

• 5” x 1’

• 3/4” x 3/4” x 7-1/2”(Spiral Rib)

X

Y

7-1/2”

3/4”

1616 1414 1212 1010 88 77

L H

.064 .079 .109 .138 .168 .188

Engineers are asked to gravitate to thin gage for CMP

15

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Str

engt

h C

ontr

ibu

tion

, %

RCP 50 psi 22 psi 14 psi

Pipe Type or Stiffness

Pipe Strength vs. Installation Contribution

Pipe Soil

Pipe Different means Installation & Inspection Must be Different

17

Type 1:Type 1: Highest quality installation using select granular soils with high compaction requirements for haunching and bedding.

Type 2:Type 2: Allows silty granular soils with less compaction required for haunching and bedding.

Type 3:Type 3: Allows use of soils with less stringent compaction requirements for haunching and bedding.

Type 4:Type 4: Allows use of onsite native material for haunching and bedding with no compaction required. (6” of Bedding is required if rock foundation)

All Backfill Requirements above to spring line ONLY

Standard Installations for RCP

Do 0.83Do0.67Do

Do

Do

6

3

Do

1.33Do

LOWER

SIDEFILL

ZONE

HAUNCH

COMPACTION

HAUNCH

COMPACTION

MIDDLE BEDDING,

UNCOMPACTED

OVERFILLOVERFILL

LOWER

SIDEFILL

ZONE

SIDD Type 1 Installation For RCP

Do 0.5Do

Do

Do

6

3

1.33Do

HAUNCH HAUNCH

SCARIFY

MIDDLE BEDDING

SITE SITE EXCAVATED EXCAVATED

BACKFILLBACKFILL

SITE SITE EXCAVATEDEXCAVATEDMATERIALMATERIAL

SITE SITE EXCAVATEDEXCAVATEDMATERIALMATERIAL

SIDD Type 4 Installation For RCP

NEW KYTC RCP INSTALLATION

For every action there is an equal and opposite reaction.

Load resisted by backfill!

Traffic Load

Earth Load

Bedding

Foundation

R1

Initial Backfill

Final Backfill

Haunching

Flexible Pipe

AASHTO Section 30 - Thermoplastic Pipe30.5.4. Structural Backfill

• 200mm (8 inch) loose lift thickness

• 90% compaction required

• Compact both sides simultaneously

• Structural fill 300mm (1 foot) above pipe

• “….shall be worked into haunch area and compacted by

hand”

• Compaction equipment within 1000mm (3 feet) of the

pipe shall be approved by the engineer

• Minimum Cover for Construction Loads

23

ASTM D 2321-Thermoplastic Pipe

• Minimum densities 85% to 95%

• Recognizes “numerous flexible pipe products” &

“inherent variability of natural ground conditions”

• Install and compact in 6” maximum layers

• Use hand tampers or vibratory compactors

• Haunching: Work in around pipe by hand to ensure

uniform support

• Do not permit compaction equipment to contact and

damage the pipe

1.33xO.D 1.25xO.D.+1.0’

STRUCTURAL BACKFILL 96% COMPACTION

SOIL/GRANULAR EMBANKMENT 85%

COMPACTION

(Type 4 Installation)

RIGID PIPE FLEXIBLE PIPE

12”

6”

Specifications/Std Drawings Must Address Differences

1.33xO.D

STRUCTURAL BACKFILL 95%

(HAUNCH)

(Type 1 Installation)

1.25xO.D.+1.0’

STRUCTURAL BACKFILL 96% COMPACTION

Flexible pipe

12”

6”

If You Do Not Build The Block

See UTA, KY & Ohio L/V Inspections of Installed HDPE Pipe

See UTA, KY & Ohio L/V Inspections of Installed HDPE Pipe

26

80% - 90% of Structure from Pipe

LOW BID INC.

RCP

85% - 95% of Structure from Backfill Material

What Do You Want The Structural Integrity of Your Design To Depend On?

Inspection During Construction• During Install.

Flexible Pipe = confirm design calcs & conditions + Firm Foundation + Homed joints + Structure/Design must be confirmed by compaction testing of pipe envelope material (the structure)

Rigid check class = plan design (structure confirmed at plant 3EB) + Firm Foundation + Joints in home position before backfill placed

Backfill for flex. Pipe = Structural Integrity of the flex. Pipe system!

28

Post Construction Inspection• Post Installation Inspection

Flexible check deflection 100% of pipe (over deflection will lead to failure)

Must combine video with some way to measure deflection L/V or Mandrel

Rigid visual inspect 100% Video 30” and smaller We are not concerned about critical inspection of

our product

29AASHTO SECTION 30.5.6NEW INSPECTION REQUIREMENTS FOR HDPE PIPE(AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)

• All pipes shall undergo inspection during and after installation.• Final inspections shall be conducted no sooner than 30 days after

completion of installation and final fill.• The pipe shall be evaluated to determine whether the internal diameter

of the barrel has been reduced more than 5 percent when measured not less than 30 days following completion of installation.

• For locations where pipe deflection exceeds 5 percent of the inside diameter, an evaluation shall be conducted by the Contractor and submitted to the Engineer for review and approval considering the severity of the deflection, structural integrity, environmental conditions, and the design service life of the pipe. Pipe remediation or replacement shall be required for locations where the evaluation finds that the deflection could be problematic. For locations where pipe deflection exceeds 7.5 percent of the inside diameter, remediation or replacement of the pipe is required.

• Installed pipe deflections that exceed 5 percent of the initial inside diameter may indicate that the installation was substandard. appropriate remediation, if any, will depend upon the severity of the deflection.

• In all pipe installations, at least 10 percent of the total number of pipe runs representing at least 10 percent of the total project footage on the project shall be randomly selected by the Engineer and inspected for deflection. Also, as determined by the 100 percent visual inspection in Section 30.5.6.1, all areas in which deflection can be visually detected shall be inspected for deflection.

30

AASHTO SECTION 26.5.7NEW INSPECTION REQUIREMENTS FOR CMP (AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)

• CMP shall be inspected after placement in the trench, as required during backfilling, and after completion of installation to ensure that final installation conditions allow the pipe to perform as designed.

• Final internal inspections shall be conducted on all buried CMP installations to evaluate issues that may affect long term performance. Final inspections shall be conducted no sooner than 30 days after completion of installation and final fill.

• It should be noted that the AASHTO Flexible Culvert Liaison Committee has been directed to write deflection criteria for inclusion in the installation specification for CMP this year.

• As of ’06 7.5 max deflection established!

31

AASHTO SECTION 27.6.1NEW INSPECTION REQUIREMENTS FOR RCP (AS ADOPTED BY THE AASHTO SUBCOMMITTEE ON BRIDGES AND STRUCTURES – JUNE 29, 2005)

• Internal inspections shall be conducted on all buried rigid pipe installations to evaluate issues that may affect long-term performance, such as cracks, joint quality and alignment. Inspections shall be conducted no sooner than 30 days after completion of installation and final fill.

• Hairline longitudinal cracks in the crown or invert indicate that the steel has accepted part of the load. Cracks equal to or less than 0.01 in. (0.25 mm) in width are considered minor and only need to be noted in the inspection report.

• Inspection records for pipes with crack widths exceeding 0.01 in. (0.25 mm), shall be kept on file for monitoring conditions during subsequent inspections. Crack measurements and photographs shall be taken for monitoring conditions during subsequent inspections.

32

Specifications and Std. Details• Review and use national Stds as a guide to

complete your own Specs for the diff. piping products

• Materials & Manufacturing• Installation• Inspection

• Allow us to be a resource & provide you with all the national stds. and suggested specification outline for all Products

Risk & Liability Issues

• Hydraulics• Flammability• Pre-Mature Structural Failures• Environmental Issues

ab

34

Hydraulics• Laboratory testing is done with perfect

laminar flow conditions and the pipe is not subjected to external loading

• Both concrete and plastic pipe have achieved laboratory “n” values of 0.009

• What additional losses can be attributed to the “rippling” of the interior liner under field loading conditions?

Hydraulics

36

38

24” Pipe Slope = 0.5%

LAB ACTUAL VALUE VALUE

0.012 = Manning’s n = 0.018 24” = Inside Diameter = 23.62” 245 = 1.49/n x A x R x S = 156 17.32 cfs = Q = 11.03 cfs

HDPE pipe will only carry 64 percent of the 17.32 cfs water that it was intended to carry. Need to use 30” HDPE pipe instead.

2/3 1/2

Hydraulic Efficiency

Recap - Hydraulics

• Manning’s “n” value Critical• “n” for HDPE, closer to value

of CMP• Risk to Owner/Engineer =

undersized pipe, upstream flooding, asset losses, liability

40

Flammability

Low Risk ? -- High Maintenance -- Value?

42

Premature Failure Are a Cost that affects us all!

43

Culvert Failures…

How much do they ACTUALLY cost?

I – 35 W Bridge CollapseMinneapolis, MN

• Measures the present value of all relevant costs of installing, operating and maintaining alternative drainage systems over a specified period of time. engineering construction maintenance rehabilitation replacement

Economic AnalysisLife Cycle Cost Analysis

46

WASTEWATER = D-

INCLUDES SANITARY AND STORM SEWER

It is unwise to pay too much, but it is worse to pay too little.

When you pay too much, you lose a little money. When you pay too little, you

sometimes lose everything, because the thing you bought was incapable of doing

the thing it was bought to do.

The common law of business balance prohibits paying a little and getting a

lot-it can’t be done. If you deal with the lowest bidder, it is well to add

something for the risk you run. And, if you do that, you will have enough to pay

for something better. JOHN RUSKIN 1819-1900, renowned English critic, social commentator, and economist of the Victorian Age

48

RCP VS Flexible Pipe SystemsDIFFERENT IN MANY WAYS!• IF YOU TAKE ANYTHING AWAY WITH

YOU TODAY WE WANT YOU TO CLEARLY UNDERSTAND:

RIGID PIPE IS DIFFERENT FROM FLEX. PIPE

Recognize The Differences:• MUST BE DESIGNED DIFFERENT• MUST BE INSTALLED DIFFERENT• MUST BE INSPECTED DIFFERENT

SPECIFICATIONS AND DETAILS SHOULD BE DIFFERENT

49

Sleep Better With Concrete Pipe