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

[mred2]

My boss had land cleared, (beside the interstate hwy), to build a new building with access road. Took 65 feet from top of hill, solid rock. A lot of the rock was push to the back in a deep hole. So no hill behind him. A much bigger site. The cost was almost a million dollars and a time frame of 9 months. He still have to pay for the water and electric to come in. Could not get natural gas, cost was too high blasting thru rock.
You need to see what soil, rock and how deep. If you go 10 feet and hit solid rock, you have have wasted time and money. Some rock is not as hard to dig in. The local USGS should have soil maps you might check first. In that area of the country, I would want an engineer to talk to.

 

[Rebeldad1]

Watched a high end log house build on tv. The owner bought the top of a mountain with a insane great view.
Needed to take the top of the mountain off for the build site. Believe around 130 truck loads of mountain was hauled away. The didnt give a cost but had to be expensive. The home was built and over 10 million spent there.

 

[Ocean2026]

All good suggestions thanksI do have an idea as to the dirt as they built logging roads and can see the parts of the hill were cut out. Very few rocks and at the top part of the property there have been a few slides or were before the vegetation kicked it. This land was Weyerhauser and they logged it completely. In addtion the folks who did the soil survey will contact me with their information.

I do gather I can't move too much earth in a week but I can get a better feel for the project. Its also true that I'm a beginner but did some dozer work 15 or so years ago and really enjoyed it.

I guess this might be better for a backhoe however.

 

[airbiscuit]

Why not build a switchback road for access and a house with a nice walkout basement or tuck under garage, with a nice wrap around deck above? Forget the massive leveling.

 

[Ocean2026]

I've watched some videos on swtchback and thought about making a road-trail to the top with much less leveling. Is the slope of 25% too steep for a backhoe?

 

[RickB]

Given your rather obvious lack of experience and understanding of the challenges you face, why not get local engineering guidance? Construction of a steep driveway with switchbacks requires attention to details concerning drainage and surface stability.
Free Internet forum advise is sometimes worth exactly what you pay for it.

 

[mikester]

I've watched some videos on swtchback and thought about making a road-trail to the top with much less leveling. Is the slope of 25% too steep for a backhoe?

Sounds like you have never operated a BH on steep slopes. Top up your life insurance before proceeding. I wouldnt attempt it without a tracked machine.

Great view!

 

[deezler]

I guess this might be better for a backhoe however.

WAT. You can't be serious with this. You think a backhoe can level a 500-ft square area by removing 160 vertical FEET of native soil? You have somewhere between 600,000 and a MILLION yards of soil to move, by my very rough calculation. A million full loader buckets to transport, dump and compact off the edge.... would take literal years of constant work. And after that, if you somehow succeed, you will have a 160 ft tall cliff at the edge of this level pad, ready to collapse and kill/bury you at any moment. Have you even investigated permits?

I think you'd better scale the plans down. Way, way down.

 

[Diggin It]

^^^ And how much diesel will be required for that? It sointently won't be cheap!!!!


Better call the Fine Howard and Fine Excavating Engineers.

Nyuk, nyuk, nyuk .......

 

[airbiscuit]

Can you be more specific about what you are trying to accomplish?

• Level an area for a house?
• Level an area for camping?
• Access Road?

Is this an area that has been logged off, and now you just climb on foot?

 

[Jim Nelson]

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]

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]

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]

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]

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]

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.

 

[Xfaxman]

This is a 2/1, 50%, 26.6° slope. The hanging tow rope shows true vertical: