Observers are concerned about the way Salem Hospital is handling earthmoving equipment during construction on the former Oregon School for the Blind grounds. They say that the work might damage historic trees. An urban forester says they may be right.
The hospital cut 32 trees earlier this month and is now grading the 8½-acre property – uneven because it is the site of an ancient river – for parking, behind a blue construction fence.
The International Society of Arborists (ISA) says possible damage to trees during construction like this includes errors like root cutting, soil compaction and smothering of roots by adding soil.
“Anybody who cares, and who looks through or over the blue wall,” says neighbor Ellen Stevens, who serves on the Greenway/Bridge Studies Group, “knows violations have been occurring for weeks.”
In December, Oregon’s Land Use Board of Appeals (LUBA) found against the hospital’s request for a variance to city code that it could install 264 surface parking spaces on the land. LUBA said the hospital could put in a maximum of only 189 spaces there.
But a board member of the South Central Association of Neighbors (SCAN), the entity that challenged the hospital, says it appears the hospital is already leveling the site for its original large design, “practically the whole site,” perhaps in anticipation of an appeal.
“We’re concerned that the hospital has started building the full parking lot, when LUBA ruled it must reduce the size,” says the board member, who does not speak for SCAN. “The expectation was that they wouldn’t start construction until a new site plan was designed. We wonder why they can’t hold off until all this is settled, because they are putting those trees at great risk.”
Plastic orange netting has been erected around many trees, but they are often inside, rather than outside, of the trees’ “drip lines,” or “critical root zone,” which lies beneath the branches above.
This distresses observers who are concerned that earth -movers are now regularly rolling too close to trees.
“The best we can do is to protect to the drip line,” says a local tree advocate. “
If you picture a wine glass on a pizza platter, the wine glass being the tree and the platter being the root system. That is really what the root system of trees looks like. Meaning the roots extend far beyond the ‘drip line.‘”
In, “Tree Protection on Construction and Development Sites,” a guidebook for the Pacific Northwest, Oregon State University and the Oregon Department of Forestry concur that vulnerable tree roots extend beyond the drip line, especially as trees grow older. The guidebook says, “a critical step in retaining healthy trees during construction… is the protraction of tree roots from disturbance.”
“Best Management” practices advocated by the guidebook include: not compacting soil in critical root zones with equipment, vehicles or even foot traffic:, not parking vehicles or equipment there, not stockpiling construction or debris there and not changing soil grade there. These practices are professional guidelines and are not codified into law.
Stevens expressed her concern to the city and says, “Although the hospital moved the netting a little in the last week, the trees are still very vulnerable. There are still machines under them.”
An urban forester not employed by the City of Salem viewed the site on January 17. The forester reports that though no torn roots were visible, it is difficult to assess damage from a perspective outside the fence. “It’s pretty blocked off from the street. You’d pretty much have to trespass to get a good sense of what’s going on.”
Also, that the work is occurring in mid-January causes the forester concern. “Healthy soil includes organic matter and empty space,” the forester says. “There are lots of channels between particles of soil that are important for air, moisture and nutrients. Heavy equipment on wet soil can ruin this structure.”
Builders who preserve soil will not only preserve living historic trees, but will have better success with any new trees that are planted.
“The integrity of the soil is vital,” the forester says. “ Working on it when it’s really wet – as it is now – can effect and destroy the structure.”
Research by the USDA Forest Service shows that for every $1 spent on urban trees, $2.70 is returned in air quality, storm water mitigation and quality of life.