TOPSOIL
PART 1 GENERAL
1.1SECTION INCLUDES
A.Stripping, stockpiling, and placement of salvaged topsoil.
.
B.Furnishing, stockpiling, and placement of contractor furnished topsoil.
1.2RELATED SECTIONS Not Used
1.3REFERENCES
A.AASHTO T 194: Determination of Organic Matter in Soils by Wet
Combustion
B.North American Proficiency Testing (NAPT) Program
C.Soil, Plant and Water Reference Methods for the Western Region (WREP)
1.4DEFINITIONS
A.Subsoils – from E, B or C soil horizon layers including heavy clay and
coarse sand.
B.Topsoil – The upper layer of soil, usually referred to as the “A” soil
horizon, which is a visually distinct, dark layer of soil considered most suitable for seed germination and the support of vegetative growth.
1.5SUBMITTALS
A.Contractor furnished topsoil test results for review.
1.Provide test results for all contractor furnished topsoil sources from
an independent soil testing laboratory that meets the following:
a.Current participant in NAPT Program.
Topsoil
PART 2 PRODUCTS
2.1SALVAGED TOPSOIL
A.Existing topsoil that is stripped and excavated from on site and then
stockpiled and spread onto completed areas and excludes the following:
1.Subsoils.
2.Rock greater than 2 inch in any dimension.
3.Materials from the pavement section.
4.Construction waste.
5.Petroleum byproducts.
6.Refuse or other manmade materials.
7.Roots greater than 2 inch in diameter or 12 inch in length.
8.Noxious weed plants.
2.2CONTRACTOR FURNISHED TOPSOIL
A.Provide contractor furnished topsoil that meets the requirements in Table
1.
1.Contractor furnished topsoil may be accepted if any submitted test
results for N, P, K, or Fe that are less than the acceptable range in Table 1, as follows:
a.Apply Nitrogen, Phosphorus, and Potassium (NPK) fertilizer
at the rates indicated on the label to the quantity and location of topsoil as shown.
Table 1 Contractor Furnished Topsoil Requirements
Parameters Test Method Acceptable Range Soil pH WREPS-1.10 or S-2.20 5.5 to 8.0 Electrical Conductivity (EC) WREPS-1.20 or S-2.30 < 4 ds/m Sodium Adsorption Ratio (SAR) WREPS-1.60 <5 Organic Matter AASHTO T 194 > 1% N (Nitrate-nitrogen) WREPS-4.10 > 20 ppm P (Phosphorous) WREPS-4.10 > 15 ppm K (Potassium) WREPS-4.10 > 150 ppm Fe (Iron) WREPS-6.10 > 10 ppm Sand WREPS-14.10 < 70% Silt WREPS-14.10 < 70% Clay WREPS-14.10 < 30% Percentage of Rock Fragments (≥ 3/8 inch in diameter) < 5%
Topsoil
B.Provide contractor furnished topsoil free from:
1.Subsoils
2.Rock larger than 1.5 inch in any dimension.
3.Trash, litter and refuse
PART 3 EXECUTION
3.1GENERAL REQUIREMENTS
A.Do not strip, stockpile, spread, or place topsoil that is covered by snow,
frozen, too saturated, or otherwise in a condition detrimental to the work.
B.Complete final grading, allow trenches to settle, and complete surface
preparation by clearing the area to receive topsoil of all trash, debris, weeds, and rock 2 inch or larger and any of objectionable material before placing topsoil.
1.Scarify to a 6 inch depth any areas such as stockpiles, staging
areas and haul roads using vertical tillage, deep soil ripping or other method.
3.2STRIP AND STOCKPILE SALVAGED TOPSOIL
A.Strip only after site clearing and grubbing is completed and before
excavation of subsoil areas begins.
1.Coordinate depths, locations, and quantities with the Engineer.
B.Store in windrows or stockpiles.
1.Do not damage or impact any existing landscape plants.
2.Grade to minimize erosion on and adjacent to the stockpiles.
3.Provide appropriate temporary erosion controls as necessary.
3.3TOPSOIL PLACEMENT
A.Place and spread the topsoil to a uniform thickness of 4 inch unless
otherwise shown.
1.Break clods and lumps with harrows, disks, or other appropriate
equipment to provide a uniform textured soil.
2.Remove and dispose of clods, stones, stumps, roots, and other
objects larger than 2 inch.
B.Place topsoil to establish final grades adjacent to paved surfaces including
walks, curbs or other hard surfaces as follows:
1.1 inch below in areas receiving seed or turf seed.
2.1½ inch below in areas receiving turf sod.
Topsoil
C.Place topsoil on sloped areas as follows:
1.On slopes flatter than 3:1, disc or harrow the placed topsoil along
the contour or cat-track the placed topsoil with tracked equipment perpendicular to the contours to create continuous cleat tracks that run parallel with the contours.
2.On slopes 3:1 and steeper, cat-track the placed topsoil with tracked
equipment perpendicular to the contours to create continuous cleat tracks that run parallel with the contours.
D.Provide a suitable topsoil surface that meet the following conditions:
1.Lightly compacted to a firm surface with a friable or crumbly soil
texture.
a.Re-work any topsoil surface that is over-compacted, hard, or
crusted by cat-tracking, discing, or harrowing the topsoil surface.
2.Free from noxious weeds and other undesirable plants that have
germinated and are actively growing.
a.Remove plants growing in topsoil by hand or mechanical
methods, or by appropriate chemical herbicide application.
3.Free from soil erosion.
4.Maintain suitable topsoil surface conditions until seed, turf seed or
turf sod is completed.
END OF SECTION
Topsoil
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Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 845–848 of 1,331.
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