Minimum Best Management Practices (BMPs)

Regardless of whether a permit is required pursuant to this chapter, all grading, grubbing and stockpiling activities shall provide BMPs to the maximum extent practicable to prevent damage by sedimentation to streams, watercourses, natural areas and the property of others. It shall be the permittee's and the property owner's responsibility to ensure that the BMPs are satisfactorily implemented. A. Drainage. On-site drainage shall be handled in such a way to as to control erosion, prevent damage to downstream properties and to return waters to the natural drainage course in a manner which minimizes sedimentation or other pollution to the maximum extent practicable. B. Dust control. All areas disturbed by construction activities shall control dust emissions to the maximum extent practicable through the application of BMPs, that may include watering with trucks or sprinklers, erection of dust fences, limiting the area of disturbance, and timely grassing of finished areas. C. Vegetation. Whenever feasible, natural vegetation, especially grasses, should be retained. If it is necessary to be removed, trees, timber, plants, shrubbery and other woody vegetation, after being uprooted, displaced or dislodged from the ground by excavation, clearing or grubbing, shall not be stored in or deposited along the banks of any stream, river or natural watercourse. The director may require the removal and disposal of such vegetation from the site within a reasonable time but not to exceed three months. D. Erosion controls. All disturbed areas shall be stabilized with erosion control measures that may include: staging construction: clearing only areas essential for construction; locating potential nonpoint pollutant sources away from steep slopes, water bodies, and critical areas; routing construction traffic to avoid existing or newly planted vegetation; protecting natural vegetation with fencing, tree armoring, and retaining walls or tree wells; stockpiling topsoil, covering the stockpile to prevent dust, and reapplying the topsoil; covering or stabilizing all soil stockpiles; using wind erosion control; intercepting runoff above disturbed slopes and conveying it to a permanent channel or storm drain; constructing benches, terraces, or ditches at regular intervals to intercept runoff on long or steep disturbed or man-made slopes; providing linings or other method to prevent erosion of storm water conveyance channels; using check dams where needed to slow flow velocities; using seeding and fertilizing, mulching, sodding, matting, blankets, bonded fiber matrices, or other effective soil erosion control technique; and providing vehicle wheel wash facilities for vehicles before they leave the site. E. Sediment control. In addition to the erosion control measures of this section, providing practices to capture sediment that is transported in runoff to minimize the sediment from leaving the site. Filtration and detention (gravitational settling) are the main processes used to remove sediment from construction site runoff. Sediment control measures include sediment basins; sediment traps; filter fabric silt fences; straw bale, sand bag, or gravel bag barriers; inlet protection; stabilized construction entrances, and other measures to minimize off site tracking of sediment by construction vehicles; and vegetated filter strips. F. Material and waste management. Measures to insure the proper storage of toxic material and prevent the discharge of pollutants associated with construction materials and wastes shall be implemented. G. Timing of control measure implementation. Timing of control measure implementation shall be in accordance with the approved erosion control plan if such plan is required. At a minimum disturbed areas of construction sites that will not be redisturbed for twenty-one days or more will be stabilized (grasses or graveled) by no later than the fourteenth day after last disturbance. H. The use of soil as fill is prohibited within any shoreline area, as defined by chapter 205A-41, Hawaiʻi Revised Statutes, except for sand as defined in section 20.08.020 . I. Any grading of a coastal dune within the shoreline area or a frontal dune, is prohibited except that sand may be imported and placed on the area of the coastal dune mauka of the shoreline, with a grading permit required by section 20.08.040 for the purposes of rebuilding or enhancing the protective capacity and environmental quality of the coastal dune. J. Upon prior approval of the director, sand that is blocking a drainage outlet may be removed to the minimum depth necessary to allow for the passage of flood waters. Any sand removed shall be placed on the adjacent shoreline. (Ord. 3135 § 6, 2003: Ord. 2684 § 5, 1998)