for Highway Construction Page 173 of 71 5 SECTION 213 – TOPSOIL
213.01 Description.
Excavate suitable topsoil from stockpiles, sources outside the roadway, or from its natural position within the right of way that will be occupied by the roadway. Place and key in the topsoil on designated constructed cut and fill slopes and other designated areas after grading operations are complete.
213.02 Materials.
Obtain topsoil from approved sources from the soil profile A horizon layer that has a friable, loamy character and contains an organic matter amount normal to the region. Obtain topsoil from well -drained arable land that d oes not contain subsoil (from the soil profile B horizon layer), refuse, roots, heavy or stiff clay, stones larger than 1 inch, coarse sand, sticks, brush, litter, pesti cides, contaminated soil, noxious weeds, or other material detrimental to vegetative growth and establishment. Ensure the county weed authority has visually inspected approved sources for presence of noxious weeds before delivery or placement . Test sources if noxious weeds are located within or adjacent to the source site, and obtain approval from the county weed authority or authorized personnel from the Department or Idaho State Department of Agriculture that the source is acceptable to use on the project site. Incorporate vegetative matter into topsoil, except brush, trees, or noxious weeds. Other deleterious material (e.g., plastic, glass, metal, rocks) will not exceed 0.1 percent by weight or volume. Provide microorganism inoculants that contain a diverse mix of regional specific mycorrhizal species for specific condition, provide macronutrients and micro- nutrients that are tolerant of chemical imbalances in the soil, produce humic compounds and binding compounds, and improve soil structure. Soil Amendments .................................................................................................................... 711.18 Remove and di spose of vegetation at topsoil sources before taking materials from the source. Provide topsoil as specified below in Table 213.02- 1 and Table 213.02-2 . Table 213.02-1 – Topsoil Gradation Sieve Size Percent age by Weight Required to Pass a Square Mesh Sieve 1 in 98 - 100 No. 4 95 - 100 No. 8 80 - 100 No. 200 15 - 80 for Highway Construction Page 174 of 71 5 Table 213.02-2 – Topsoil Chemistry Property Minimum Maximum pH (a) 5.5 7.8 ESP (b) — 10.0 EC (c) — 8.0 Organic Material 0.5 15.0
a.pH: Negative logarithm of the hydrogen ion concentration
b.ESP: Exchangeable sodium percentage
c.EC: Electrical conductivity, milliohms per cm at 77°F
213.03 Construction Requirements.
Remove, treat, and process all areas containing noxious weed seeds and/or plants with herbicide applications or by specific heat treatments and material rotation for composted material. Process composted material (heat and rotation) for at least 90 calendar days to kill all viable weed seed and plant material. Test topsoil to verify the topsoil is free of viable noxious weed seed or plant parts, herbicides, fungicides or other chemical residues harmful to plant or animal life. Obtain a representative composite topsoil sample 2 months before final placement and seeding applications to determine soil pH, nutrients, and organic materials present. Provide a soil analysis by an North American Proficiency Testing -Performance Assessment Program (NAPT -PAP) accredited laboratory to determine if extra nutrients (fertilizer ingredients) and organic materials (mulch or compost) are needed to amend the soil, and verify the soil does not contain noxious weeds. The following labs are accredited to perform the required tests:
1.Stukenholtz Laboratory; Twin F alls, ID.
2.Northwest Agriculture Consultants; Kennewick, WA. Collect 15 random soil samples fr om at least 3 different locations and thoroughly mix and homogenize the samples into a single composite sample. Sample all changes in soil (e.g., color and texture changes ). Submit 1 composite sample to an accredited soil laboratory for s oil testing and analysis. Obtain a soil analysis report with original soil pH, fertilizer, and organic material content, as well as recommended soil amendments to be incorporated into the topsoil before beginning subsequent revegetation activities. Excavate to a depth of at least 6 inches, unless otherwise directed. Place topsoil excavated from the roadway directly on cut and fill slopes without use of stockpiles whenever conditions and work progress allows . Where this procedure is not possible, excavate topsoil and stockpile within the project site. Stockpile topsoil so natural drainage is not disturbed or causes offsite sediment transport. Surround topsoil stockpile with BMP sediment controls. Treat topsoil stockpiles with temporary soil stabilization measures immediately upon stockpile completion. For topsoil stockpiles exceeding a height of 4 feet that are undisturbed for longer than 3 months, mix the top 1 foot with the rest of the stockpile to ensure that living organisms are distributed throughout the stockpile at the time of final placement, or add microorganism inoculants after final placement in acc ordance with the for Highway Construction Page 175 of 71 5 manufacturer’s written instructions. Apply microorganism inoculants as dry granular mixes, tablets, or injectable soluble. Do not place topsoil until the areas to be covered have been properly prepared. After final slope grading and before topsoil placement , all slopes will be roughened or cross -ripped in a horizontal direction to the slope to assist in anchoring the topsoil. Rip shank spacing will be 36 inches and a maximum 12 -inch penetration depth or as directed. Topsoil placement on smooth slopes is not allowed. Following slope preparation, distribute topsoil to all disturbed areas to be reseeded or revegetated during the specified seeding window. Place to psoil, spread, and key into the underlying material by the use of harrows, rollers, or other suitable equipment or methods. Ensure the minimum topsoil placement thickness is 6 inches unless otherwise specified.
A.Soil Imp rovemen ts. Soil improvements consisting of fertilizer and soil amendments (e.g., soil nutrients, organic materials, or combinations) or soil conditioner will be approved by the Department, including the type and quantity for each improvem ent as determined by a laboratory soil analysis and recommendation. Add and lightly incorporate soil improvements by spreading on the topsoil surface and raking into or incorporating into the top 1 to 2 inches of the topsoil before subsequent seed bed preparation activities as specified in 621.03.B. For 2.5H:1V slopes or steeper, or where hydroseeding is specified, soil improvements may be added to the mulch mixture and applied during the hydroseeding application, if approved. For dri ll seeding applications, apply soil conditioner before seeding and lightly incorporate into the soil wherever possible.
213.04 Method of Measurement.
The Engineer will measure acceptably completed work as follows:
1.Topsoil obtained from the roadway and placed directly on designated slopes or placed in stockpiles will be by the cubic yard in its original position.
2.Topsoil obtained from the roadway and construction areas and placed direc tly upon cut and fill slopes, ditch bottoms, and other designated areas will be measured by the square yard in its final location.
3.Topsoil measured by the square yard will be parallel to the slope.
213.05 Basis of Payment .
The Department will pay for accepted quantities at contract unit price as follows: Pay Item Pay Unit Topsoil .................................................................................................... CY or SY The Department will pay for topsoil excav ated from the roadway at the excavation contract unit price as specified in 205. The Department will pay for topsoil in its final p osition, which includes the cost to stockpile if necessary, and to haul to the project site where it is to be placed and finished on the slope. for Highway Construction Page 176 of 715 The cost to provide and incorporate soil amendments, including fertilizer and/or organic mater ials is incidental . for Highway Construction Page 177 of 715 SECTION 214 – ROADSIDE CLEANUP
214.01 Description.
Remove and dispose of stumps, foundations, debris, and boulders and perform minor leveling and drifting of material between the limits of clearing and right of way only as specified or as directed. The Department will not pay for neces sary cleanup resulting from the Contractor’s operations.
214.02 Materials.
Not specified.
214.03 Construction Requirements.
Not specified.
214.04 Method of Measurement.
The Engineer will measure acceptably completed work as specified in 109.03.
214.05 Basis of Payment .
The Department will pay for acceptable quantities as follows: Pay Item Pay Unit Roadside Cleanup (Contingency Item) ................................................... CA
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 209–212 of 768.