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Wind Load Topographic Effects

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I hope my wind questions are not wearing on the list. I am trying to
interpret section 6.5.7 Topographic Effects.

Mean Height exceeds least horiz dimension therefore use Method 2.

Considering a 20' square by 35 foot tall enclosed structure located about
50' downhill from a relatively level area (escarpment)at the top of a hill.
The downhill slope is about 3 to 1 and is generally open grasses for an area
about 200 feet wide and about 800 feet down the hill. Surrounding this open
area are dense tall redwood trees. I do not know the topography at the
bottom of the hill beyond the redwoods, however the slope does continued
down into the forested area, but where it levels off I do not know.

I am confused by items 1 and 2 of section

Is the hill considered to be obstructed by the large trees on the sides of
the open area and 800 feet down the hill?
How do I determine H and Ln?
At what point is the hill no longer a hill?

>From a first pass I get ranges of Kzt of 2.54 for a 2 diminesional ridge,
1.85 for a 2-D escarpment. But if section does not apply it would be

Happy New Year.


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