Correspondence iN151 - 2010 --00 I Z-9
T H E P A C I F I C R E S O U R C E S G R O U P
LAND MANAGERS • URBAN FORESTERS • PLANT APPRAISERS • NATURAL RESOURCE CONSULTANTS
August 25, 2010
Mr. Mark Seaman
8407 SW 58th
Portland, Oregon 97219
Reference: Tree Assessment for 2 lots at SW 92n & North Dakota Street, Tigard, Oregon
Dear Mr. Seaman,
At your request, I visited 11285 SW 92 & SW North Dakota Street, the site of your two Tots. The purpose
of my visit was to meet with you and determine which trees remain on the two lots and which trees could
be retained with the building footprints that you are proposing to build on each lot. For the original 2 -lot
partition I assessed 35 trees that were shown on the tree survey. Two of the trees (tree 34 & 35) are
located on the adjacent property and remain in place. As part of the partition street improvements,
sidewalk, driveway and utilities were installed in the North Dakota right of way. This necessitated the
removal of trees including trees 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 & 33. These trees
were either directly in the way of proposed improvements or suffered severe root loss during grading and
installation of the required improvements. The root loss left some of the trees unstable and unsafe to
leave standing. 1 recommended their removal.
When 1 inventoried the trees back in 2005, I identified 3 hazard trees (trees 1, 29 & 32) that were dead or
dying and had other serious defects. I recommended they be removed whether development proceeded or
not. Tree 29 was removed because it suffered root loss during installation of utilities and became an even
greater hazard. Tree 1 was toppled in a windstorm in November 2008 and was subsequently removed.
Fortunately it fell into the unoccupied part of the lot and caused no damage. Tree 32 remains, but is still a
hazard and should be removed.
When we met on site this week, I looked at the building footprints that you had staked out. It looks like
you can retain those trees that are at least 12' or more from the homes. Assuming that root loss is as
expected, the trees that will be preserved after construction of the two homes include trees 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 17 and 31. It will not be possible to determine if the trees closest to the proposed
homes can be left in a reasonably stable and healthy condition until excavation is underway and the
extent of any root loss or filling over the roots is apparent. If any trees suffer significant loss of major
structural roots, I will recommend their removal.
Most of the original tree protection fencing remains in place. When we met I suggested tree protection
fencing locations that would allow you to excavate for the home foundations without intruding on the
tree protection zone. When I returned to the site today all the tree protection fencing had been installed.
When the foundations have been excavated you should call me so 1 can assess any root loss that might
occur. I should also be notified if it becomes necessary to move any of the tree protection fencing or to
work within the tree protection areas. I will also plan to make periodic inspections when construction is
active and provide you with field reports to meet the City's requirements.
As mentioned in my 2005 report, in addition to protecting the trees from inadvertent physical injury, the
tree protection fencing should serve to minimize any soil compaction that might occur within the trees'
root protection zone. This will require keeping construction materials, soil, foot traffic and equipment out
of the area within the tree protection zone to the extent practical. The fencing should protect as much of
the root protection zone as possible, without including the excavation for the utilities, foundation walls,
etc. If it is necessary to work closer to the tree than this or to work inside the tree protection fencing, you
should notify me
I still recommend that any trees which are retained, be provided a fertilization program that will help
promote root growth following construction. For any newly planted trees the fertilization can be delayed
until the next growing season. To accomplish this I recommend that the landscape contractor or new
home owner fertilize the entire area beneath the preserved trees using a highly soluble high nitrogen
fertilizer applied at a time when surface vegetation is dormant and tree roots are still growing. The best
time to do this is in late October or early November and/or in mid to late February. The fertilizer is best
applied just prior to or during a rain, otherwise it should be watered into the soil. I recommend using
Ammonium Sulfate (21 -0 -0 or 23 -0 -0) at a rate of 2 lbs. of Nitrogen per 1000 square feet of area treated.
This equates to applying 9 lbs. of the fertilizer to each 1000 square feet of area within the drip line of
each tree or woody plant. The annual amount of Nitrogen that should be applied is between 2 to 4 lbs. per
1000 square feet, the first year, and half that amount in subsequent years. If a single application is made,
it should be done in late November, otherwise two applications of nitrogen can be made, one each in late
fall and early spring. The fertilizer can be applied to the surface of the ground with a cyclone or "whirly"
type spreader. The fertilization should be done within the drip line and to an area a few feet outside the
drip line. To determine the area to be treated for trees such as this, with the tree at the center, the area to
be treated is within the circle that has a radius equal to one foot for every inch of the tree's diameter.
After the first application I recommend that you take soil samples to determine existing nutrient levels
and get a recommendation on the composition of fertilizer or other soil amendments that are needed by
the plants on site. Contact A & L Western Agricultural Lab at 503- 968 -9225 for soil analysis instructions
and assistance. Once the partition is completed and Tots are offered for sale, this information should be
passed on to the new homeowners of those lots containing any of the preserved trees.
This completes my report. If any additional information, which would effect my observations or
recommendations becomes available I would welcome the opportunity to consider it and revise this
report accordingly. If I omitted any information or if you have any questions please do not hesitate to
contact me.
Respectfully yours,
Stephen F. Goetz, Principal
American Society of Consulting Arborists, Reg #260
American Society of Landscape Architects, Oregon Lic. #80
Society of American Foresters
SG:mac
Attachment