Nev. Admin. Code § 444.8384 - Capping fill trench: Design criteria
1. The soil
surrounding and beneath the bottom of a capping fill trench must have a
percolation rate that is greater than 2 minutes per inch, but less than or
equal to 120 minutes per inch. The required area of the absorption trench must
be determined by calculating the size of the effective sidewall pursuant to
subsection 11 of NAC 444.8354.
2. A
minimum depth of 4 feet must be maintained between the bottom of the capping
fill trench and the level of the seasonal high groundwater, any impermeable
barrier or any other limiting features.
3. A capping fill trench must not be
installed on a slope that is greater than 10 percent.
4. The invert of the disposal drain pipe must
be placed not more than 12 inches below the existing grade of the native soil.
At least 2 inches of aggregate must be placed above the disposal drain pipe.
Untreated building paper, straw, geotextile fabric, or any other similar
covering approved by the health authority, must be placed above the aggregate
before the placement of the capping fill.
5. The absorption trenches must be
constructed before the capping fill is constructed.
6. The capping fill must extend at least 10
feet beyond the sidewall of the absorption trench. The vegetative mat in the
fill area must be disrupted by scarification or plowing. The owner of the
system shall take such precautions as are necessary to prevent compaction of
the scarified area. No vehicles may travel on the capping fill.
7. The native soil and the applied fill must
be mixed at their point of interface. The soil to be used as fill must be of a
texture similar to the native topsoil. The fill must be placed over the
aggregate to a depth of not less than 12 inches or more than 18
inches.
8. The fill must be evenly
graded to provide positive drainage away from the absorption trenches and
toward the perimeter of the capping fill. The fill material must be placed in
such a manner so as to prevent the compaction of the scarified soil at the
interface of the native soil and fill. Plant vegetation must be established on
the top of the fill to reduce the potential for the erosion of the capping
fill.
9. A capping fill trench must
not be used if the soil in which the capping fill is to be placed exhibits
saturated conditions.
10. The
following is a diagram of a capping fill trench:
Click here to view image.
Notes
NRS 439.200, 444.650
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