What Wood Preservative Good for Field Application for a Deck near a Lake

[Hydrostru]

I am designing a boardwalk near or on a lake, and the boardwalk will consist of pressure treated timbers.

Now I have a dilemma brought up by a contractor.

The IRC said field-cut ends and holes need to be treated in the field in accordance with AWPA M4. And the AWPA M4 recommends Copper Naphthenate or Inorganic Boron which is not good for ground contact so it leaves me only with Copper Naphthenate. But EPA said "Treated lumber (with Copper Naphthenate) must be stored under cover, indoors, or at least 100 feet from any pond, lake, stream, wetland, or river to prevent possible runoff of the product into the waterway. Treated lumber stored within 100 feet of a pond, lake, stream, or river must be either covered with plastic or surrounded by a berm to prevent surface water runoff into the nearby waterway. If a berm or curb is used around the site, it should consist of impermeable material (clay, asphalt, concrete) and be sufficient height to prevent runoff during heavy rainfall events."

And the product Woodlife Coppercoat (which contains Coper Nphthenate) said in its technical data sheet that "do not apply at sites near or on water or wetlands"


So my questions is for wooden decks/boardwalks near or in water, what preservative shall be used/specified for field treatment? Thanks.

 

[XR250]

what portions of the deck are ground contact?

 

[SlideRuleEra]

There is an important exemption to AWPA M4:
"Exceptions (to treating field cuts and holes) can be made when the wood is a thick sapwood species such as Southern pine, has very little heartwood, and appears to be well treated."

See if Southern Pine is being used, and that the treatment level is adequate (or better) for the application. In the USA most treated lumber is Southern Pine. If so, additional treatment of cuts and holes is not needed.

See this AWPA webpage for verification of the above statement:

http://www.awpa.com/references/official.asp

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net