1. SCOPE
The work shall consist of stripping, stockpiling, site preparation, and spreading topsoil in accordance with the applicable specifications.
2. STRIPPING
Strip topsoil only from those areas that will be disturbed
by excavation, filling, road building, or compaction by equipment. A 4 to 6 inch stripping depth is common, but
depth varies depending on site.
Determine depth of stripping by taking soil cores at several
locations within each area to be stripped.
Topsoil depth generally varies along a gradient from hilltop to toe of
the slope.
All planned erosion and sediment control practices shall be in place and functioning properly prior to stripping.
3. STOCKPILING
Select a stockpile location to avoid slopes and natural
drainageways, and to avoid traffic routes.
On large sites, respreading is easier and more economical when topsoil
is stockpiled in small piles located near areas where they will be used.
Perimeter controls shall be placed around the stockpile
immediately. Examples of suitable
control measures include DIVERSION DIKE 820, SILT FENCE 920, and STRAW BALE
BARRIER 935.
Temporary stabilization of the stockpile shall be completed
within seven (7) days of the formation of the stockpile, in accordance with
practice standard TEMPORARY SEEDING 965, if it is to remain dormant
(undisturbed) for longer than thirty (30) days.
Permanent stabilization of the stockpile shall be completed
within seven (7) days of the formation of the stockpile, in accordance with
practice standard PERMANENT VEGETATION 880, if it is to remain dormant
(undisturbed) for longer than 12 months.
4. SITE PREPARATION
Before spreading topsoil, assure that all necessary erosion
and sediment control practices such as diversions, berms, dikes, waterways, and
sediment basins are in place and functioning properly. These practices must be maintained until the
site is permanently stabilized.
Grading - Maintain grades on the areas to be topsoiled
according to the approved plan and do not alter them by adding topsoil.
Liming of subsoil - Where the pH of the existing subsoil is
6.0 or less, or the soil is composed of heavy clays, incorporate agricultural
limestone in amounts recommended by soil tests or specified for the seeding
mixture to be used (Practice PERMANENT VEGETATION 880). Incorporate lime to a depth of at least 2
inches by disking.
Roughening - Immediately prior to spreading the topsoil,
loosen the subgrade by disking or scarifying to a depth of at least 4 inches,
to ensure bonding of the topsoil and subsoil.
If no amendments have been incorporated, loosen the soil to a depth of
at least 6 inches before spreading the topsoil.
5. SPREADING TOPSOIL
Uniformly distribute topsoil to a minimum compacted depth of
2 inches on 3:1 slopes and 4 inches on flatter slopes. To determine the volume of topsoil required
for application to various depths, use Table 1.
Topsoil shall not be spread while it is frozen or muddy or
when the subsoil is frozen or muddy.
Irregularities in the surface that result from topsoiling or
other operations shall be corrected to prevent the formation of depressions or
water pockets.
Compact the topsoil enough to ensure good contact with the
underlying soil, but avoid excessive compaction, as it increases runoff and
inhibits seed germination and seedling growth.
Light packing with a roller is recommended where high-maintenance turf
is to be established.
In areas that are not going to be mowed, the surface shall
be left rough.
FOR
APPLICATION TO VARIOUS DEPTHS
|
DEPTH (in.) |
PER 1,000 FT.2
|
PER |
|
2 |
6.2 |
269 |
|
3 |
9.3 |
403 |
|
4 |
12.3 |
537 |
|
5 |
15.4 |
672 |
|
6 |
18.5 |
807 |