Leveling part of a hill iwith a 25% Slope- see atttachments

Jim Nelson · Aug 11, 2020

If any of the pad or access roads are going to be built with fill material the fill needs to be started with a key way at the toe (bottom) of the slope and it needs to be an engineered fill put in in compacted lifts with soil compaction tests as it comes up.This will require a geologists report and soil analysis. The best way to do it is with a dozer of adequate size and compaction equipment such as a sheepsfoot. The face of the slope will also need to be compacted. I worked heavy construction for 40 years and built several of this type of project and can assure you it's no place for a "green" hand

texas42 · Aug 13, 2020

So, we are all talking about the same thing, attached drawing explains % slope and angle of slope
Normal highway slope is 2 horizontal to 1 verticalView attachment Slopes Explained.pdf

JamesHW · Aug 13, 2020

I went ahead and looked at what the USDA Soil Survey for that hill reported and if the specifics are correct (not always true at that scale) it says your slope, at least the upper half is comprised of the following soil type:

Grays Harbor County Area, Pacific and Wahkiakum Counties, Washington

148—Umbric Dystrochrepts, very steep

Map Unit Setting

National map unit symbol: 2gkr
Elevation: 20 to 1,800 feet
Mean annual precipitation: 60 to 110 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 170 to 230 days
Farmland classification: Not prime farmland
Map Unit Composition

Umbric dystrochrepts and similar soils: 100 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Umbric Dystrochrepts

Setting

Landform: Bluffs, gullies, canyons
Parent material: Colluvium and residuum derived from basalt
Typical profile

H1 - 0 to 8 inches: gravelly sandy loam
H2 - 8 to 20 inches: gravelly loam
H3 - 20 to 24 inches: unweathered bedrock
Properties and qualities

Slope: 85 to 99 percent
Depth to restrictive feature: 10 to 20 inches to lithic bedrock
Drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity: Very low (about 2.4 inches)

Xfaxman · Aug 14, 2020

texas42 said:
So, we are all talking about the same thing, attached drawing explains % slope and angle of slope
Normal highway slope is 2 horizontal to 1 verticalView attachment 666132

I wondered if anyone wound notice the 25% Slope in the title of this thread.

25% slope is only 14 degrees, not steep at all:

25° is a 47% slope, steep and hard to walk on:

RickB · Aug 14, 2020

Xfaxman said:
I wondered if anyone wound notice the 25% Slope in the title of this thread.

25% slope is only 14 degrees, not steep at all:
View attachment 666204

25° is a 47% slope, steep and hard to walk on:
View attachment 666206

He also is describing a 160 foot vertical cut.

Jim Nelson · Aug 14, 2020

In all my years working heavy construction I never saw a slope shown as % or degree, the were always shown and staked as 1.5/1,2/1 etc. The steepest slopes I ever encountered were 1/2/1 and that was in open pit mines and looks vertical to the naked. I landscaping there were a lot od 3/1 and 4/1 etc. . As noted the first number is horizontal and the second is vertical.Grade checkers kept track of progress using a hand level and engineers folding rule to place progress stakes every 3 to 4 feet. Surveyors placed stakes at the top of cut slopes like the op is talking about or at the bottom of fill slopes.
Usually the steepest fill slopes allowed are 2/1 and, depending on the type of material, cut slopes may be as steep as 1.5/1 but in modern times are more likely to be 2/1.