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Topsoil Design Guidelines

Current PDF Version of This Guideline

Topsoil is to be provided for in the contract and installed by the contractor prior to the site being turned over to UNC. The Designer shall approve all topsoil prior to installation. The Contractor shall provide soil tests for any topsoil brought onto the site, and obtain approval from the University before delivery. The Contractor shall insure that all topsoil is screened so that it contains no material larger than 1.0 inches in diameter or length and shall not contain slag, cinders, stones, lumps of soil, sticks, roots, trash, or other extraneous materials. The Contractor shall insure topsoil is free of plants or plant parts of Bermuda grass, Johnson grass, nutsedge, poison ivy, or other noxious weeds.

Prior to topsoil application, the contractor scarify the soil areas where topsoil is to be applied to a depth of one foot (1′) and remove and haul off all construction debris before spreading the topsoil. No scarification or subsoiling should be done within the dripline of any existing tree. The first 4” of topsoil needs to be mixed into the scarified top layer of existing soil. Continue adding soil in 4” lifts until finish grade is established.

A minimum of four inches (4”) of topsoil is to be applied in all disturbed areas. A minimum of twelve inches (12”) of topsoil is to be applied in all landscape plant bed areas. Exceptional care should be taken when spreading topsoil around trees. Soil around existing trees should not exceed the grade which existed prior to construction. Grade lawn areas and beds to conform to finish grades and profiles indicated on drawings, assuring uninterrupted drainage pattern, free of hollows and pockets. In areas where subgrade is poorly drained, provide corrective drainage indicated on drawings. If these measures do not correct drainage notify Architect for his direction prior to further work.

Topsoil should be purchased pre-mixed or mixing should be done off site prior to soil testing unless otherwise approved by Architect.

  • 3 parts sandy-loam topsoil with additive required to bring pH to 5.5-6.5 range.
  • 1 part composted pine bark organic material

Clean Up

After the soils have been ripped, and before the required topsoil is spread, and final grades approved, clear the site of all surface trash and other objects that will hinder the installation and maintenance of the planted areas. The clean up includes plant bed areas, lawn areas, rights-of-way adjacent to the site, buffer areas, and lay down areas.

Surface Drainage of Planted Areas

The Contractor shall bear final responsibility for proper surface drainage of all areas within the project

Stabilization (grassing) of Disturbed Areas

Repair and seed all areas that are disturbed during construction. Till disturbed area to a depth of 6 inches. Incorporate 18-24-12 fertilizer at a rate of 10 lb. per 1000 square feet. Evenly distribute Turf Type fescue blend grass and perennial rye seed at a rate of 10 lb. per 1000 square feet. Lightly rake seeded areas, mulch with 1″ clean wheat straw, and water thoroughly. Areas that will be converted to plant beds can be stabilized using pine straw or organic mulch.