Specifications include, but are not limited to: The work covered by this specification consists of overall maintenance for the City of Omaha’s (City) Hanscom Park Green Infrastructure Facility (Hanscom Park GI). Stormwater runoff from west of Hanscom Park will drain into a structure that discharges a design peak flow to a screening structure to remove trash and debris before entering the west bioretention system. Once full, flow will bypass the bioretention system, enter an outlet structure that will convey that flow to the east bioretention systems. Flow from the park road will enter the north, east bioretention system (cobblestones). Once full, flow will bypass and enter an outlet structure where flow will discharge into the Hanscom Park Lagoon. Bioretention Soil Mix (BSM) • BSM shall consist of 85% to 90% (by volume) course sand and 10 to 15% (by volume) organic compost. • Course sand shall be clean and free of toxic materials. • Compost shall be Oma-Gro as produced by the City of Omaha’s compost facility located at 15705 Harlan Lewis Road, Bellevue, Nebraska 68123, 402-444-6665 • The soil mix shall be properly mixed prior to placement. Mixing shall occur to ensure that course sand and organic compost are thoroughly and evenly mixed and a consistent texture is achieved throughout. Mixing shall occur on a hard surface. Provide clean mixing conditions to ensure foreign objects, including other soils, are not introduced during the mixing process. Do not mix materials in wet conditions or conditions that would cause soil clumps to form. Materials shall not be mixed on site unless approved by the City Point of Contact.
