Friday, September 21, 2012

Preservative-treated wood is a natural choice


Preservative-treated wood is a natural choice for construction projects in our public lands.



Preservative-treated wood is an economical, durable, andaesthetically pleasing building material; therefore, it is a natural choice for construction projects in our National Forests, National Parks, and other public lands. However, we need to ensure that the chemicals used in treated wood do not pose a threat to people or the environment. 

The waterborne wood preservatives chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA),ammoniacal copper quat (ACQ), copper dimethyldithiocarbamate(CDDC), andammoniacal copper citrate (CC) resist leaching during service because of complex chemical reactions that take place within the treated wood. The effectiveness of these reactions in preventing leaching is dependent on treating factors, such as preservative formulation, preservative retention, and processing techniques, as well as post-treatment conditioning factors, such as temperature, humidity, and air flow. Copper naphthenate, an oilbornewood preservative, resists leaching because it is relatively insoluble in water. Little information is available on the inserviceleaching rates of any of these wood preservatives, although CCA has been studied more extensively than the other preservatives.

Past studies report widely varying leaching rates, but generally agree that the most rapid leaching occurs within the first months of service and is greatest in products with high retention levels and high proportions of exposed surface area, especially end-grain. Leaching is also increased by exposing the wood to high water flow, low pH, and water-soluble organic acids. Movement of leached chromium and copper appears quite limited in soil, because the metals are tightly bound to organic soil constituents.

 Arsenic is slightly more mobile in soil, but binds to iron, aluminum, and manganese. Generally, the preservative components are least mobile in organic soils, slightly more mobile in clay soils, and most mobile in sandy soils. In aquatic applications, the leached preservative components form complexes with the organic sediment fines, and accordingly are either deposited or moved downstream with the sediments. Additional research is needed to characterize typical in-service leaching rates of these preservatives and to determine how processing parameters affect long-term leaching rates.

Lebow, Stan. Leaching of wood preservative components and their mobility in the environment—Summary of pertinent literature. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.



Pressure Treated Wood Preservatives 

Wednesday, September 19, 2012

BUILDING A BOARDWALK- Plastic Lumber WWFF-25


BUILDING A BOARDWALK- Plastic Lumber

Many manufacturers of recycled plastic are producing this material in the shapes and dimensions of standard wood lumber and timber products. Some of these products are being marketed as premium deck coverings. Recycled plastic can be worked like wood. It can be sawed, drilled, nailed, screwed, bolted, and painted. Although the surface is smooth, it is not slippery.

Photo- The decking and railing (grey color) are plastic products, the supports 
and posts are PT lumber- Boyd Hill Nature Preserve. This product is
older, and newer products are of better quality.


The properties of some recycled plastic may present unexpected challenges and disappointments. The material can be up to three times heavier than wood. By itself, 100-percent recycled plastic has little strength. It must be reinforced with a steel backing or core to have any structural value, increasing its weight and introducing another material. Plastic is rot resistant, and can act to keep the wood lumber below it drier and extend the structures useful lifespan.

 The thermodynamic properties of plastic-how much it expands and contracts in the heat or cold-are quite different from those of concrete, steel, or wood, the materials that would normally be used with recycled plastic. The surfaces of some recycled plastic severely degrade in sunlight. The problems of strength, thermodynamics, and ultraviolet degradation are being studied. These problems have resulted in new, improved formulations of recycled plastic. These products have not yet withstood the test of time.

Some recycled plastics contain sawdust or another form of wood fiber or fiberglass. These composites are usually stronger and do not have the same thermodynamic problems as most 100- percent plastics. When sawed or drilled, the exposed sawdust and wood fiber may be just as subject to fungus and insect attack as untreated wood. However, wood fibers completely encased in plastic will still be rot resistant. Fiberglass resists rot. Composites containing fiberglass are rot resistant.

A problem is created when any of the recycled plastics are drilled or sawed in the field. Unlike wood, the shavings and sawdust will not decompose. This problem can be resolved by drilling and sawing over a large plastic sheet and carrying the shavings out.  Recycled plastic is not a traditional construction material. It may be inappropriate where a rustic appearance is important.

 Recycled plastic costs 50 to 300 percent more than treated wood. The increased weight of plastic will be reflected in higher shipping and onsite construction costs. One advantage of this plastic is that it does not support combustion.


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BUILDING A BOARDWALK- The Hand Rail WWFF-24


BUILDING A BOARDWALK- The Hand Rail

A pedestrian railing system may be needed along the edge of a deck to prevent visitors from falling off. If you are planning to install a pedestrian railing, the details of the installation of the posts need to be thought out before placing the deck. Railing posts need to be sturdy. They are a potential liability. Flimsy railings installed as an afterthought are the ones most likely to fail. Usually, it is the connectors, not the railing, that fails.




During floods, the posts and rails can catch debris and form a dam. In most situations it is better to build as little as possible that will have to resist the force of high-velocity floodwaters. A decision on how much or how little to build should be based on the type and age of the visitors who will use the finished facility-schoolchildren, senior citizens, day hikers, or backpackers.

The deck, posts, and handrail are all closely related in their construction. As a minimum, 4 by 6 timbers should be used to support handrails. Actually 4 by 4s that are surfaced on all four sides are only 3½ by 3½ inches. They make a flimsy post. The deck should extend beyond the stringers to the back of the post, or at least 4 inches. If this is not done, people standing on the deck and leaning on the railing will have their feet sticking out beyond the deck.




The best method is to attach the posts to the outside of the stringers. It is much easier to bolt the post in place before attaching the adjacent deck plank. To provide solid support, 12 inches of post should contact the stringer. The posts can be accurately cut and drilled in a shop and brought to the site. To avoid the awkward and time-consuming work of notching the planks, the width of the post should match the width of the deck planking.

If hard plastic or pliable plastic covers are not used on the top exposed posts, they should be cut at an angle to shed water and to help prevent rot. To avoid a sharp corner at the top of the post, a narrow 1-inch area closest to the handrail should be cut level, and the sloping portion should be pitched away from the boardwalk. For esthetic and safety reasons, the posts should not extend above the top of the handrail.

Handrails for more remote trail bridges must be at least 42 inches high for pedestrian traffic and at least 54 inches high for bicycle or equestrian traffic. These handrail systems must also have at least one intermediate rail so that vertical distances between rails do not exceed 15 inches.

Not all wetland trail structures need railings. If the trail itself has more hazardous drops than the trail bridge would have without a handrail, a handrail is probably not required. Other considerations, such as convenience, may justify installing a handrail. As a general rule, any fully accessible trail with a drop of 4 feet or more should have a pedestrian railing system. 



All accessible trails should at least have a curb. A wheelchair handrail is required for any accessible trail bridge on a grade of 5 percent or steeper.

Install the railings after the posts and deck are complete. Most railings consist of a top and bottom rail, usually 2 by 6s, although 3 by 6s make a better splice and a stronger rail. The stronger rail permits posts to be spaced more widely than if 2 by 6s were used for rails. The rail can also be cut and drilled in a shop where the splices can be cut accurately and more efficiently.

Curb and bull rail are two names for the same thing. If the drop from a boardwalk is about 30 inches or less, a curb is usually installed. A curb is required for accessible trails. Curbs present a potential tripping hazard for pedestrians.



Curbs placed directly on the surface of a wood deck can cause the deck planking to rot. Leaves, needles, and dirt accumulate against the curb, absorb water, and cause additional rot. During the winter, ice and snow will build up on the deck, causing a hazardous condition. To keep the deck from rotting, place the curbs on blocks. A finished block of 2 by 4 lumber is only 1½ inches thick. Leaves and dirt can still build up against the curb and under it. With just 1½ inches of space between the curb and the deck, it is difficult to get a shovel under the curb, making this area almost impossible to clean. A better solution is to use two blocks of 2 by 4 lumber, one on top of the other, or one block of 4 by 4 lumber. The increased clearance under the curb will not trap litter, and melting ice and snow will run off more quickly.



BUILDING A BOARDWALK- The Deck WWFF-23


BUILDING A BOARDWALK- The Deck

A boardwalk is a structure that uses widely spaced bents or piers as a foundation. 



Stringers, parallel with the center line of the boardwalk, rest on the ledgers of the bents or piers. The stringers support the deck, which is usually 2 by 6 or 2 by 8 lumber laid perpendicular to the center-line and nailed or screwed to the stringers, or to nailers bolted to the stringers.

 Boardwalks usually have a curb or handrail along their edges.

Basically, a boardwalk is a series of connected bridges, each with a span as long as is practical, perhaps 8 to 20 feet. At most wetland sites, longer stringers are not practical because they are difficult to transport.At least two stringers or beams rest on the ledgers and span the space between consecutive bents or piers. As the space between bents or piers increases, a third stringer, or heftier stringers, must be used.

Long, thick stringers are more expensive than smaller ones. However, they permit the bents or piers to be farther apart.



Ideally, the bottom of the stringers of a boardwalk should be above high-water levels, but this is often impractical. To reduce maintenance, the design of the boardwalk should avoid interference with the flow of floodwater and floating debris.The height of anticipated floodwater may seriously affect the design of a proposed handrail.

Often boardwalks are found around visitor centers, heavily used interpretive trails, or at other high-use sites. The sophisticated construction and materials needed for a boardwalk are less appropriate in the backcountry where the trail user expects simpler, more rustic construction and more challenging facilities.





Tuesday, September 18, 2012

Trails are important as we measure who we are as Americans WWFF-22


Trails are important as we measure who we are as Americans and as individuals.


“These times of challenge can seem daunting, but as a nation, we have gone through crises before and each time we have emerged stronger and better. These are times when we look both within ourselves and to leaders to navigate troubled waters. 

As people who care about the American landscape and our relationship with it, it will be a time when we will be called upon to share our talents and to lead. What we do as trail and greenway advocates will not be superfluous or trivial in these times and here is why. Maintaining the integrity of our values as a nation is a paramount element of weathering tough times. 

Our landscape and how we treat it has been, and must remain, important. It is more than just aesthetics, because our relationship with our natural resources is a key aspect of this crisis— as the fires out west demonstrated. Our physical, mental and spiritual health is equally important. Trails and greenways are important in this picture.  So where DO we fit in? Through our work, we need to convey a message. That message needs to be about a sense of stewardship in our wild lands and open spaces. 

Wildfires and mosquitoes carrying West Nile virus might challenge these values when people feel less safe. We will need to improve our skills, learn more, and help people learn to better live with a troubled landscape that ultimately must sustain us. We need to explore ways that greenways and trails improve the economic well-being of states and communities and how trails and greenways promote better health and fitness.” -Bob Searns

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"We know that the United States spends more for health care than any other nation on earth- an estimated $3,358 per person, that is 14 percent of our gross national product. We have also learned that in order to keep costs down, future health care strategies must focus on prevention.

The most important prescriptions for creating effective preventative care are regular exercise and a moderate diet. According to the 1990 Healthy People 2000 report, there is increasing evidence that light to moderate physical activity, often associated with recreation behavior, can have significant health benefits. The report recommends several appropriate actions, including significant investments in recreation resources, such as areas for hiking, biking and swimming." -Texas Parks and Wildlife

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“Look for a discussion of Nature in psychology texts and you will usually find next to nothing.  Animal research in psychology normally consists of controlled laboratory procedures with rats, monkeys, pigeons, or flatworms. 

Sunsets, waterfalls, lunar eclipses, a bolt of lightning, rainbows, a fresh snowfall, a tapestry of wildflowers in a mountain meadow, the sweet lusty evening song of a warbling vireo, the haunting hoot of an owl, majestic snow-capped mountains at sunset and towering redwood trees thrusting up into a fog bank, seldom, if ever, get any column inches in our psychology texts.

 These are the books that set the standards of what we should think of ourselves. It is as if Nature had no significant influence on our lives! "We are victims of academic, scientific, and even therapeutic psychology, whose paradigms do not sufficiently account for ". . . that essential mystery at the heart of each human life," James Hillman has declared. I could not agree more. 

Until Nature is factored into our psychology we cannot become whole, and our ability to avoid environmental catastrophes is hindered. There have been efforts to articulate the man-nature relationship, principally "deep ecology" and "eco-psychology." Both have made valuable contributions, and both also at times become political movements as much as scholarly pursuits. 

But more importantly, what do you feel when you are on the trail? -James A. Swan, Ph.D


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“To best increase the use of your trails, you must ensure that the trail experience itself is a quality one. 

Enhancing the trail experience is needed to encourage repeat use and continued safe, appropriate use. There are many tools and strategies that can lead to establishing the best practice of enhancing the trail experience. Great Trails are well planned and designed, well-constructed, and well maintained to ensure they are safe, readily accessible and aesthetically satisfying.

 Great Activities meet the needs and expectations of trail users. Great Trail Users ensure the long-term viability of the trail or the experience through commitment and stewardship.

Great trails and great trail activities must be promoted to achieve the desired goal of increased trail use. It is important, however, to make the distinction between information promoting the trail and the detailed information required to get people to and around the trail in safety. 

Potential users must be made aware of what trails and activities exist, and must be provided with the necessary information to use the trail and/or participate in the activity. Both marketing and information tools, however, can include brochures, maps, signage, trail guides, web sites, e-navigate communications, branding, advertising, media coverage and special incentives.

 Develop and commit to a public relations plan. Brand your trail or experience. Provide clear and accurate trail information. Create a website providing easy access to current information and virtual experiences. Establish mutually beneficial marketing relationships. Finally, make friends with the media to have a “Force Multiplier” for your promotions budget.” - Hike Ontario