Laserfiche WebLink
media cells shall be placed over the treatment media. Additional treatment media shall be <br /> placed over the plant support media to within 2 inches of the top of the vault. <br /> PLANTS <br /> The plants shall be installed at a minimum of four per treatment chamber, or two feet on center. <br /> An estimated minimum 4 plants will be required within the stormwater treatment vault. The <br /> Engineer shall approve the final layout and distribution of shrubs prior to installation. A <br /> recommended plant distribution shall be as follows: <br /> Plant Name Size Quantity <br /> Perovskia atriplicifolia 1 Gallon 4 <br /> The Contractor shall ensure that plants have a 95 percent plant survival rate. <br /> No external water source will be provided for plant establishment. The installation of gator bags <br /> or approved equal shall be provided. <br /> Biofiltration Catch Basin <br /> Contractor shall furnish a one (1) year maintenance contract provided by the Manufacturer to be <br /> coordinated directly with the County. Annual maintenance consists of two (2) scheduled visits <br /> per year for the first year. <br /> Each Biofiltration Catch Basin maintenance visit consists of the following: <br /> • System inspection <br /> • Foreign debris, silt, plant material and trash removal <br /> • Filter media evaluation <br /> • Plant health evaluation and pruning <br /> • Replacement of plant material <br /> • Disposal of all maintenance refuse items <br /> • Maintenance records updated and stored <br /> Control Structure <br /> Each unit shall consist of a precast 60" diameter Type 2 catch basin with all material necessary <br /> to construct a flow restrictor in accordance with the plans. <br /> Infiltration Chamber Gallery <br /> Inspection ports shall be installed as shown on the Plans prior to backfilling. <br /> Subgrade Preparation and Subbase <br /> Installation of the facilities shall be performed according to the chamber manufacturer's <br /> latest installation guidelines. The performance of these infiltration facilities is highly <br /> dependent upon avoiding compaction of the soils beneath the infiltration facilities. The <br /> Contractor shall develop a plan to minimize compaction beneath each facility. The <br /> Engineer must approve this plan prior to facility excavation. <br /> Stormwater Detention Tank System <br /> Stormwater detention tank system shall be pre-fabricated tanks designed and approved under <br /> the supervision of a professional engineer licensed in the State of Washington. Shop drawings <br /> shall be submitted to the Project Engineer for approval. <br /> Swift Green Line—Corridor Stations Special Provisions SP98 <br /> May 2017 <br />