Does this apply to Cut Pads only or Fill Pads as well?
You can use the Overex command on the Pads.
You want Overex to be 2’ - this is the specified Overexcavation number
However you also want to limit the overex to only 2’ below OG (not 2’ below any pad elevation whether in cut or in fill) i.e. if the Pad is already 3’ cut you don’t want to overex a further 2’ below the pad therefore you want to limit the Maximum depth beneath the original ground to 2.0’
You may want to always excavate at least 2’ of existing ground under the pads, in which case you can specify 2.0’ in the Minimum Depth beneath Original Ground.
However if you don’t need to overexcavate fill pads when the depth of Fill exceeds 2’ then you can set the Minimum beneath original ground value to 0. This is the control for what happens below Fill Pads i.e. when this value is 0 and the Fill is greater than 2’ then there will be no overex. If the fill is only 1’ then the overex of 2’ kicks in and takes out 1’ of existing to give 2’ of select fill below the pad.
So to summarize - there are 3 main settings in the Overexcavation calculation
Specified Overexcavation
This is the amount of overex required below the bottom of subgrade on the defined overex areas e.g. 2.0’. Where and when this is applied is controlled by the next two settings
Minimum beneath original ground
In a fill situation - this number controls whether or not you have to overex at least a minimum depth of material regardless of the depth of fill being placed under the bottom of subgrade.
For example
If your Specified Overexcavation is 2.0’ and your fill below subgrade is already 3.0’ and this setting says 0 then no overex of original ground will take place.
If your Specified Overexcavation is 2.0’ and your fill below subgrade is 3.0’ and this setting is 1.0’ then 1.0’ will be removed from OG below the Pad subgrade to meet the 1.0’ setting.
Maximum depth beneath original ground
In a cut situation - this number controls the depth of additional required overexcavation below the pad subgrade
For example
If your specified overexcavation is 2.0’ and your cut at base of subgrade is already at 3.0’ and this setting is set to 2.0’ then no additional overexcavation will be required.
If your specified overexcavation is 2.0’ and your cut at base of subgrade is already at 1.0’ and this setting is set to 2.0’ then an additional 1.0’ of overexcavation will be required.
If your specified overexcavation is 2.0’ and your cut at base of subgrade is already at 3.0’ and this setting is set to 10.0’ then an additional 2.0’ below the pad subgrade will be required to meet the specified overexcavation and maximum depth criteria.
Limit to top of stratum checkbox
If for example you have Topsoil (to be stripped) then soil and then weathered rock and then bedrock as strata layers in the geology for a project. In some cases the overex requirement can be to a specific stratum layer top, or a specified depth below a stratum layer e.g. 1.0’ below Weathered rock.
Where you are limited to the top of stratum, check this checkbox and then pick the strata layer that you want to use from the list of strata in the strata list for the project.
If you need to be e.g. 1.0’ below top of weathered rock, then you will need to create an extra strata layer in your strata list called Weathered Rock -1.0 and set the depth of that surface to be 1.0’ below the Weathered Rock strata in the boring logs / strata list. Then you can select that adjusted strata layer in the pull down list here to overex to that layer of material.
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