03-06: Attachment D - Palm Park Soil Stripping Stockpiling and Treatment — original pdf

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Palm Park Soil Stripping, Stockpiling, and Treatment 29 May 2026 GENERAL The purpose of this guidance document is to provide instruction and support for stripping existing horticultural soils at Palm Park and stockpiling the soils for re-use after other construction activities affecting soil conditions have been completed. The following procedures for soil stripping and stockpiling are recommended to be implemented to conserve soil quality. • The Contractor shall examine previous work, related work, and conditions under which this work is to be performed and notify the Landscape Architect in writing of all deficiencies and conditions detrimental to the proper completion of this work. • Identify all areas in which soil is to be conditioned in place and set up Vegetation and Soil Management Zones (VSMZs). o VSMZs will be identified with orange construction fence. o Other than soil conditioning machinery, trucks or other heavy equipment shall not be allowed in VSMZs. Ingress and egress of equipment into VSMZs shall be limited to once a day. o SOIL STRIPPING • Prior to stripping soils for salvage and re-use, existing vegetation shall be removed from the soil. o Cut vegetation. Cutting involves removal of above ground plant matter as close to the ground as possible. • Prior to starting soil stripping work, the Contractor shall examine existing soil conditions at locations where this work is to be performed and notify the Construction Manager in writing of all deficiencies and conditions detrimental to the proper completion of this work. o o The Contractor shall be responsible for verification that all of the project areas to be stripped have been identified and mapped properly per drawings and specifications. Inspect all surfaces to check for consistent soil conditions, including soil texture, unstable areas, and areas requiring additional removal of debris, plants, or excess soil. During the inspection, use a soil probe to assess soil quality to be certain of the depth that uniform soil texture extends below the soil surface and that no compacted layers exist or buried debris is within 18 inches of the surface. o Verify that subgrade and drainage components of the areas scheduled to be stripped are without ponded water or saturated soil. o Submit any and all noted discrepancies which will impact the proper execution of the work to the Landscape Architect prior to beginning soil conditioning processes • The contractor shall be responsible for ensuring no soil compaction will occur from construction traffic or other soil stripping activities. Damage caused by construction equipment or other construction activities will be repaired by the landscape contractor at no additional cost to the owner. • Verify that the surface moisture content is suitable for soil stripping and stockpiling. Under no circumstances shall the contractor strip and stockpile soil when the soil is too wet. • Existing topsoil: Stripping topsoil will be done by stripping the topsoil to a depth of 9-12 inches below the ground surface. Subsoil will be then be stripped to a depth of 12 inches below the topsoil, or to the depth of the pre-existing subgrade soil, whichever is shallower. • Remove any gravel or other debris that may exist on the surface. • Appropriate topsoil stripping depth shall be determined as the depth of soil color and without large clay clods that can be found in the subsoil on site. • All soil stripping shall be completed with minimal damage to surface soil structure (compaction, smearing, balling). Soil stripping shall not be conducted with soil is wet, or within 24 hours of a rainfall of ½-inch or more. SOIL TRANSPORT AND SCREENING • Stripped soil shall be transported to stockpile locations along planned corridors only. Other than soil stripping machinery, trucks or other heavy equipment shall not be allowed on areas where soil has not been stripped. SOIL STOCKPILING • Soil stockpiles are being established to conserve and build healthy salvaged soils that will support vegetation in the park. All stockpiles shall be appropriately labeled with signs identifying the origin of the stockpiled material. o Stockpile locations will be selected to avoid slopes and natural drainageways, and to avoid traffic routes. o Prior to placement of soils into stockpiles, the stockpile site shall be prepared by grading the stockpile pad level with a 2 percent grade in direction of drainage. • Install ventilation Pipe consisting of 4” diameter Schedule 40, smooth, rigid, perforated HDPE pipe. o Layout: Lay aeration pipe horizontally in the soil stockpile. Pipe shall extend from the face of the stockpile by a minimum of 18”. Pipes shall be placed approximately 6- to 18 inches above ground level. Ventilation pipes will be placed 8 feet apart for each layer. Slope pipes at 1.0% toward the downslope position. o The requirement for Ventilation pipe will be waived if the height of the stockpile does not exceed 6 feet. o Salvaged soils shall be placed on stockpiles to a height not to exceed 8 feet. • Soil shall be placed and graded across the pile in a single pass of low-ground pressure equipment (tracked bulldozer exerting less than 6 pounds per square inch ground pressure). • The top of the stockpile shall have minimum 2 percent grade to the outer perimeter. The sides of the stockpiles shall have 2:1 slopes. o The surface and sides of the soil stockpile shall be prepared to have a firm, friable, seedbed. • Density of the soil stockpiles shall not exceed 80 percent of maximum dry density as determined by Standard Proctor testing (ASTM D6938 - 17a Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)). • Perimeter controls shall be placed around the stockpile immediately. Examples of suitable control measures include diversion dikes, silt fence, or straw bale barriers. • Temporary stabilization of the stockpile shall be completed within 3 days of the formation of the stockpile. COVER CROP PLANTING AND MAINTENANCE • Stockpiles shall be top-dressed with 1 inch of compost to provide temporary stabilization and short-term plant nutrients. • Within 3 days of completion of the soil stockpile, a cover crop consisting of annual rye grass shall be seeded into the compost and soil. • The cover crop shall be maintained during the stockpile’s existence. Maintenance shall include: Irrigation during initial seed germination and early growth (2-month period expected) o o Cover crops shall be mowed when flowering to prevent seed-set, if necessary. o Removal of invasive species. Monitoring will be conducted monthly to inspect for the presence and removal of invasive plant species. • Stockpiles shall be examined and sampled every week to assess soil structure. PROTECTION OF WORK • Protect all project areas from construction traffic, compaction, and erosion. Keep the construction site clean of all trash and debris prior to, during and after construction operations have ceased. Keep the areas clear of unauthorized personnel or equipment where planting soils have been placed.