for Highway Construction Page 513 of 715 SECTION 620 – PLANTING
620.01 Description.
Provide and plant live cuttings, seedlings, and container plants including trees, shrubs, vines, and ground cover as specified.
620.02 Materials.
Provide an equal mix of live cuttings, seedlin gs, container plants , or combinations of and obtain plants except live cuttings, from a local or regional Idaho vendor. The supplier must hold a current and valid Idaho seller/dealer’s license. Certify plants are true to genus and species. Substitutions of other genus or species will not be approved. Match the existing species composition of the surrounding vegetation for species to be planted within wetland areas. Provide materials as specified in: Topsoil ..................................................................................................................................... 213.02 Plants ...................................................................................................................................... 711.06 Commercial Fertilizer ............................................................................................................... 711.07 Soil Conditioner ....................................................................................................................... 711.08 Mulch ....................................................................................................................................... 711.10 Irrigation Water ........................................................................................................................ 711.13 Seeding and Vegetation Special Guaranty .............................................................................. 107.21
620.03 Construction Requi rements.
Perform planting operations between September 15 and May 15, when ground is not frozen and take advantage of favorable planting conditions unless otherwise approved. Clear and remove only vegetation as necessary for construction operation. Grade and level area(s) to be planted before staking or marking planting locations. Mark out and stake tree locations and the general planting area layouts for shrubs, vines, and ground cover. Do not begin planting until the tre e locations and planting site general layouts are approved. Cultivate planting areas for shrubs and vines to at least 4 inches deep. Remove and dispose of weeds and other vegetative growth, rocks larger than 1 inch, and other debris encoun tered in the cultivating work. When excavating holes for planting, keep topsoil separate from subsoil and make loose and friable. Remove and dispose of soils containing a pH greater than 8 or less than 5, stones greater than 1 inch, or other detrimental material encountered in the excavation. A soil auger may be used if approved. Adequately barricade excavated planting holes that are left open when the work is not in progress with appropriate warning devi ces. Sufficiently roughen glaze d surfaces inside planting holes before backfilling. Have the Engineer inspect all plants before planting and determine if plants are acceptable. Install plants approximately 6 f eet on- center in a random pattern as specified after completing final grading and seedbed preparation requirements. Install plants during their dormant stage and allow container plants to remain dormant through the winter. Provide adequate and proper care of plant materials. Adequate an d proper care includes keeping plant materials in a healthy, growing condition by appropriate handling, storing, watering, cultivating, pruning, and spraying. for Highway Construction Page 514 of 71 5 If planting during other seasons is allowed , apply approved organic wetting agents or antitranspirants in accordance with the manufacturer’s written instructions at no additional cost to the Department. Do not apply wetting agents or antitranspirants after April 15.
A.Containerized Plant Requirements. Remove soil equal to the dimensions of the container and remove the plant from the container without damaging roots, stems, or leaves. Mix soil conditioner into 6 inches of loose topsoil in the bottom of planting holes, but do not mix with the soil to be used in backfilling. Use approximately 1 cubic foot of soil conditioner per tree and 0.5 cubic feet of soil conditioner per shrub or vine, or as directed. Place the plant in the hole with soil just above the root crown, and f irm the groun d around the plant.
B.Bare -Root Plant Requirements. Mix soil conditioner into 6 inches of loose topsoil in the bottom of planting holes, but do not mix with the soil to be used in backfilling. Install bare- root plants before the leaves open or new needles have started forming. Place the plant in the hole and spread out their roots in a natural position, without bunching, kinking, or circling. Carefully place soil in the hole, filling in over the root system to just above the root crown, and firm the ground around the plant.
C.Backfilling and Finishing. Fill holes and cavities between plantings and the surrounding soil with topsoil . In their final position, plant the plants to the depth of the root collar or to the depth of the finished grade when grown in the nursery or container. After planting is completed, re- cultivate the soil surface to a depth of 2 inches or more. Finish grading planting areas after the soil has settled. Incorporate commercial fertilizer uniformly into the soil surface around trees and shrubs in accordance with the manufacturer’s written instructions. Apply mulch around the newly planted plants immediately after planting work in each area is complete and the ground is smooth and clean. Place mulch 2 to 3 inches thick. Cover the entire area of shrub and vine root systems as well as around trees. Promptly clean up and dispose of soil, discarded branches, rejected plants, or other debris (e.g., twine, rope, transit guards, wrappings). Remove mulch from plants, structures , roadway areas, and grassed areas not to be covered. Thoroughly water trees, shrubs, vines, and ground cover during and immediately after planting. Repeat watering as often as necessary until the work is accepted. Prevent areas from puddling on top of the soil surfa ce and avoid compact ion around the plants after watering. Obtain water without charge from state- owned or state- controlled water supply systems, if such exist; otherwise obtain water at no additional cost. Prune trees and shrubs when planting and remove broken or damaged twigs, branches, or roots in a manner that retains or encourages natural growth characteristics. Paint cut surfaces with a diameter of 1 inch or greater immediately with approved tree wound dress ing. If herbicides are used to control weeds, replace and maintain plants and lawn damaged by its use at no additional cost. At completion of the original planting, the Engineer will perform an inspection with the Contractor of plant material to note and correct discrepancies. Remove and replace dead plants . Leave plants that do not show for Highway Construction Page 515 of 715 expected growth, but have green leaves, stems, or buds and the Engineer will inspect a gain during the plant establishment period. After the original planting, the Engineer will periodically inspect the condition of plants and planting areas and identify apparent defects, faults, conditions, and dead plants di scovered by the insp ection. Correct apparent defects, faults, conditions, and remove, dispose and replace dead plants within 10 calendar days after notification or as directed. If infestation by insects or disease oc curs, treat plants using effective remedial measures that are good horticultural practices and in accordance with BMPs. Install temporary fence material around wetlands and areas to be protected from wildlife as specified in 61 0. Ensure planting establishment by watering, cultivating, replacing plants or mulch , and other work necessary to maintain the plants in a healthy condition, throughout the 1- year plant establishment period. If immediate replacement of dead or rejected plants is impossible due to seasonal conditions or the lack of specified plants, place a marker at the plant replacement location and replace plants during next planting season. The D epartment will require a plant establishment period of 1 year for replacement plants . Ensure the establishment of the new plantings as specified. Submit a contingency spill and prevention plan with emergency actions to be taken in the event of a spill. Prevent petroleum products, chemicals, or waste materials from dumping or entering waterways and wetlands.
620.04 Method of Measurement.
The Engineer will measure accept ably completed work as follows:
1.Plants , trees, shrubs, vines, or ground cover of the specified sizes and kinds will be by each.
2.Fertilizer will be by the ton or hundred- pound weight (cwt).
3.Soil conditioner will be by loose cubic yard, using the manufacturer’s certification of loose cubic yard when bagged or balled.
4.Topsoil will be by the cubic yard.
5.Mulch will be by the cubic yard or ton.
620.05 Basis of Payment .
The Department will pay for acceptable quantiti es at the contract unit prices as follows: Pay Item Pay Unit Topsoil .................................................................................................... CY Mulch ...................................................................................................... CY or Ton Planting Trees (Seedlings or Container) ................................................. Each Planting Shrubs (Bare- root or Container) ............................................... Each Planting Vines (Bare -root or Container) .................................................. Each for Highway Construction Page 516 of 715 Planting Ground Cover ........................................................................... Each Fertilizer (Commercial) ........................................................................... Ton or cwt Soil Conditioner ...................................................................................... CY The cost of temporary irrigation water and temporary fenc e material are incidental . The Department will make progress payments for plants at 80 percent of the contract unit price at original planting completion. The Department will pay the remaining 20 percent at plant establishme nt period completion and after defective plants have been replaced, if applicable. for Highway Construction Page 517 of 71 5 SECTION 621 – SEEDING
621.01 Description.
Apply seed, including seed bed preparation, fertilizing, seeding, mulch mixtures, mulching, mulch anchoring (mechanical or tackifiers), HECPs, erosion blankets , and watering in the areas specified. Seed all disturbed areas on the project site, including foreslope, backslope, and embankment areas , specified. The Department may require seeding operations in conjunction with 212.
621.02 Materials.
Provide materials as specified in: Topsoil ..................................................................................................................................... 213.02 Seed ........................................................................................................................................ 711.05 Com mercial Fertilizer .............................................................................................................. 711.07 Mulch ....................................................................................................................................... 711.10 Rolled Erosion Control Product (RECP) ................................................................................. 711.11 Turf Reinforced Mat (TRM) ..................................................................................................... 711.12 Water ....................................................................................................................................... 711.13 Mulch Tackifier ........................................................................................................................ 711.16 Mulch plus Tackifier ................................................................................................................. 711.17 Mulch Mixture .......................................................................................................................... 711.19 Hydraulically Applied Erosion Control Product (HECP) ........................................................... 711.22 Seeding and Vegetation Special Guaranty .............................................................................. 107.21
621.03 Construction Requirements.
A.Gene ral. Perform seeding operations as specified. Perform seeding during the season(s) specified, except for seeding used as a temporary erosion and sediment control measure. Inspect areas within the project site and identify noxious weeds present or which weeds are most lik ely to be found on the project site and include treatment recommendations. Treat material used as specified throughout the growing season, and up to 2 weeks before transporting to the project site and seeding applications. Obtain approval for all products before use. Use mechanical (drill) seeding on areas with 3H:1V slopes or flatter and areas without excessive rock, gravel, or hardpan soil. Apply fertilizer, seed, and mulch in separate operations, one following the other in this order, with the exception that fertilizer may be applied with a fertilizer attachment at seeding time or with water when watering is specified, or as otherwise approved. Perform cultivating, tilling, and dr ill seeding operations in a cross- slope direction (horizontal) and ensure furrows remain open.
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 549–552 of 768.