Preserved Wood for Marine Uses

Presented by Dallin Brooks, WWPI Executive Director

Western Wood Preservers Institute

• Represents preservative treated wood producers, chemical manufacturers and others serving the industry throughout western North America

• MissionIncrease awareness of the proper use of treated wood products by providing information to:

• Homeowners• Builders• Architects, Specifiers

• Bldg. Material Dealers• Code Officials• Ports and Marinas

2

Remember: All materials have enemies

• Concrete

• Steel

• Wood

• Auger cast piles

Concrete issues

• Spalling

• Soil displacement

• Changing pH

• Disposal

• Expensive

Steel issues

• Corrosion

• Installation alignment

• Bending

• Failure

• Expensive

Wood issues

• Marine Borers

• Preservative Movement

• Failure

Wood advantages

• Proven

• Economical

• Long-lasting

• Strong, durable, resilient

• Availability in emergencies

• Domestically ̶ often locally ̶ produced

• Natural appearance

• Rugged handling

• On-site modification

• Renewable

• Low energy production

• Carbon storage

• Minimal on-site waste

Hurricane resistance

• Home in Pearlington, MS• Reportedly only home

to survive flooding from Hurricane Katrina

• Water came within inches of CCA pile girders

• Similarly constructed beach houses meeting wind load standards from New Jersey to Mississippi

Hurricane resistance

• Coastal home in Galveston, Texas• Built on CCA pilings

• Survived Hurricane Ike, storm surge

Hurricane resistance

• Homes in Nags Head, NC• Built on wood piles

• Survived tropical storms, depressions in 2009

History of wood pilings

• First used 6,000 years ago• Neolithic tribes in

Switzerland

• Placed logs vertically into soft soil for structural support

• Homes built on piles to protect against wildlife

• Evidence of structures still seen today

History of wood pilings

• Roman bridges• Tiber River Bridge, built

in 642 BC

• Span lasted more than 700 years

• Roman roads, aqueducts• Supported on timber

piles

• Still in good condition 1,900 years later

How strong is today’s wood?

• Wood fiber has not changed significantly over time

• Little difference in “old wood” vs. “new wood”

• Confirmed by testing

Bending tests

• Horizontal force applied by cable at tip of the timber pile

• Results:Bending stresses could be 36% to 53%higher than currently allowed

Full-scale testing

• Tests on full size pieces conducted in 1999 and 2000

• Intended to develop design stresses

• Also tested for compression strength

• Conducted by EDM International in Fort Collins, CO

Piling design values

Property Southern Pine2

Douglas fir3

Compression Parallel to Grain, Fc 1,200 1,250

Extreme Fiber in Bending, Fb 2,400 2,450

Horizontal Shear, Fv 110 115

Compression Perpendicular to Grain, Fc 250 230

Modulus of Elasticity, E 1,500,000 1,500,000

Source: Values are from ANSI/AF&PA NDS-2005, National Design Specification for Wood Construction, Supplement for Timber Poles and Piles.

1 A form factor for bending members of circular cross section is incorporated in the allowable unit stresses for extreme fiber in bending listed in the table, for pile clusters.

2 Southern pine values apply to longleaf, slash, loblolly and shortleaf pine.

3 Douglas fir values apply to Pacific Coast Douglas fir.

Normal load duration, wet use conditions Pounds per square in. 1

Standing up to pressure

• Timber pilings well suited to withstand pressure of being driven into soil• Foundation supports

• Marine pilings

Timber pilings - foundation

• Resists attack from alkaline, acidic soil

• Corrosion protection not required

• Unaffected by electrolysis from stray electrical current

• Takes advantage of plentiful, renewable domestic resource

Timber pilings - foundation

• Installs with readily available equipment

• Wood less noisy than other driven piling

• Lowest cost per ton of load carrying capacity of any deep foundation material

Piling durability – FHWA Conclusion.

• Treated wood pilings submerged in groundwater will last indefinitely

• Fully embedded, treated, concrete capped foundation piles partially above the groundwater will last 100 years or longer

Load carrying basics

• Piles typically used with difficult conditions, weak sub-surface soils

• Pile transmit forces to a lower stratum that has sufficient bearing to support structures, applied loads

• End-bearing piles primarily transfer loads through the tip.

• Friction piles primarily transfer loads through tangential friction.

• Natural taper increases the friction reaction, recognized in design

Butt

Tip

Load tests

• Many tests conducted on load carrying capabilities• Concrete block testing

• Results show actual capacity exceed design values with wide margin of safety

• Test procedure:ASTM D1143

Test data vs. design loads

Southern Pine PilesPILE SIZE TEST DESIGN

LOAD NO. OF LOAD

LOCATION Length Butt Tips (tons) TESTS (tons)

Donaldsonville, LA 80’ and up Class B 140 & 150 1 60

Mobile, AL 60’ 14” 9.5” 140 65

Virginia Beach, VA 76’ Class A 100 50

Charleston, SC 75.8’ 14” 8.25” 118 1 50

South Pierce, FL 70’ 14” 7” 100 50

Port Arthur, TX 65’ 14”-15” 8”-9” 150 5 75

Chicago, IL 43.7’-44.3’ Class B 80 & 150 2 40

Chicago, IL 43.5’-48.2’ Class A 100 & 142 2 40

Portsmouth, VA 86’ Class A 1001 4 50

Virginia Beach, VA 40’ 1001 1 50

Scotland, LA 53’ 15” 8” 100 12 40

1 Not to failure Source: AWPI Data

Foundation piling typical sizes

Specified Tip Circumferences with Corresponding Minimum Butt CircumferencesA (from ASTM D25 -- Table X1.5)

(Approximate Diameters in Brackets)

Required MinimumTip Circumference, In 16(5) 19(6) 22(7) 25(8) 28(9) 31(10) 35(11) 38(12)

Length (ft) Minimum Circumferences 3 ft from Butt, in.20 19(6.0) 22(7.0) 25(8.0) 28(8.9) 31(9.9) 34(10.8) 38(12.1) 41(13.0)25 20(6.4) 23(7.3) 26(8.3) 29(9.2) 32(10.2) 35(11.1) 39(12.4) 42(13.4)30 21(6.7) 24(7.6) 27(8.6) 30(9.5) 33(10.5) 36(11.4) 40(12.7) 43(13.7)35 22(7.0) 25(8.0) 28(8.9) 31(9.9) 34(10.8) 37(11.8) 41(13.0) 44(14.0)40 26(8.3) 29(9.2) 32(10.2) 35(11.1) 38(12.1) 42(13.4) 45(14.3)45 27(8.6) 30(9.5) 33(10.5) 36(11.1) 39(12.4) 43(13.7) 46(14.6)50 31(9.9) 34(10.8) 37(11.8) 40(12.7) 44(14.0) 47(15.0)55 32(10.2) 35(11.1) 38(12.1) 41(13.0) 45(14.3) 48(15.3)60 33(10.5) 36(11.4) 39(12.4) 42(13.4) 46(14.6) 49(15.6)65 34(10.8) 37(11.8) 40(12.7) 43(13.7) 47(15.0) 50(15.9)70 35(11.1) 38(12.1) 41(13.6) 44(14.0) 48(15.3) 51(16.2)75 36(11.4) 39(12.4) 42(13.4) 45(14.3) 49(15.6) 52(16.6)80 37(11.8) 40(12.7) 43(13.7) 46(14.6) 50(15.9) 53(16.9)85 38(12.1) 41(13.0) 44(14.0) 47(15.0) 51(16.2) 54(17.2)90 39(12.4) 42(13.4) 45(14.3) 48(15.3) 52(16.6) 55(17.5)

A Piles purchased as “8-in. and natural taper” have a required minimum tip circumference of 25 in. and are available in lengths of 20 to 45 ft.

Wood treating yesterday, today

• Modern wood preserving began in England in 1832• The first U.S. treating plant built

in 1848

• Today’s plants have latest in environmentalprotection features

• Drip pads protected from leakage with liners below the concrete• Drippage is recaptured and

recycled.

Purpose of treating

Protection against

• Decay

• Marine organisms

• Mollusks

• Shipworms

• Boring Clams

• Crustaceans

• Limnoria (gribbles)

• Sphaeroma

• Chelura

Treatment goal

• Piling cannot be 100% penetrated, usually because of heartwood content

• Inject preservative shell around wood, providing protective envelope of treatment

• Penetration andretention requirements must be met

Sapwood

Heartwood

Treating standards

• American Wood Protection Assn. (AWPA)

• American Society for Testing and Materials (ASTM)

AWPA Marine (Salt Water) Use Categories

Treating requirements

AWPA Reference

Type PenetrationAssay

Zone(s)Retention

CCA Pcf.RetentionACZA Pcf.

RetentionCreosote Pcf.

UC4C FoundationSYP 2.5”

Dfir 0.75”0.0-2.0” 0.80 0.80 12.0-17.0

UC4C Land & FreshwaterSYP 3.0”

Dfir 0.75”0.0-3.0” 0.80 0.80 12.0-17.0

UC5AMarine - Long Island, NY, & North

SYP 4.0” Dfir 1.0”

0.0-0.5”0.5-2.0”

1.50.9

1.50.9

25.0

UC5B & 5CMarine - Long Island, NY, & South

SYP 4.0” Dfir 1.0”

0.0-0.5”0.5-2.0”

2.51.5

2.51.5

25.0

UC5B & 5C Dual treatment CCASYP 4.0” Dfir 1.0”

0.0-1.0” 1.0 1.0 25.0

UC5B & 5CDual Treatment Creo

SYP 4.0” Dfir 1.0”

0.0-1.0” 20 20 25.0

AWPA Use CategoryAWPA T1-13 Section E AWPA T1-13 Section G Marine

Assuring quality preservation

• AWPA– U1 Treatment per Label

– T1-13 Section E T1-13 Section G Marine

– A2, A9 Analysis

– A3 Penetration

• Customer requirements

• Treating company

• BMPs are available for foundation and marine applications

Environmental protection

• BMPs

• Risk assessment model

• Wraps,

• Polyurea coatings

CCA Piling Human Health Risk Assessment

• Examined risks to workers, children• Conducted by Gradient Corp.

• No documented cases of adverse health effects

• Potential health effects within EPA’s risk limits

CCA Piling Human Health Risk Assessment

• Arsenic complex present on surface and in soil; arsenic in piling bonded with wood

• Studies of carpenters, treating plant workers show no increased risk.• Amount of arsenic complex

potentially taken into body is at least 14 times less than that amount from food and drinking water

Piling Life Cycle Assessment

• Review of environmental impacts of treated wood, concrete, galvanized steel and plastic pilings

• Conducted under ISO 14044 standards

Piling Life Cycle Assessment

• Treated wood showed lower impacts in all six categories assessed

Thank you

Dallin BrooksExecutive Director

dallin@wwpinstitute.org360-693-9958