Erosion and Sediment Pollution Control Program Manual.pdf

Filter Fabric Fence -----A sediment barrier constructed from filter fabric attached to support stakes.
See Standard Construction Detail #s 4-7, through 4-10.
Filter Layer -----Well-graded, hard, durable, non-soluble particles — free from muck, topsoil, organic
matter or rubbish — or geotextile fabric, placed under slope protection to prevent the natural soil
of the bank from being washed away through the slope protection layer.
Filter Strip -----A strip or area of vegetation used for removing sediment, organic matter, and other
pollutants from runoff and wastewater.
Filtration -----The process of retaining soils and other materials while allowing the passage of water or
fluids.
Fine Particles -----Silt and clay particles, also called fines.
Fine Textured Soil -----Sandy clay, silty clay, and clay.
Finished Grade -----The final elevation of the ground surface conforming to the approved plan.
First Flush -----The first portion of runoff generated by a storm event containing the main portion of the
pollutant load resulting from the storm.
Fish and Boat Commission -----See PA Fish and Boat Commission.
Fish Habitat Enhancement Structure -----Structures such as deflectors, low flow channels, channel
blocks, mudsills, boulders, felled shoreline trees, special tire structures, brush structures, rubble
reefs, half-log structures, elevated boulder structures, and spawning/nursery structures that are
placed in streams, lakes, ponds, or reservoirs as developed and approved by the PFBC. Such
activity requires a GP-1.
Fish Ladder -----Artificial, stepped pools to enable fish traveling upstream to span a relatively large
vertical distance in a series of gradual steps, typically used at dams or other stream barriers.
Flanking -----Stream flow between a structure and the bank, possibly occurring because the structure
was not properly tied into the bank.
Flexible Growth Medium (FGM) -----An hydraulically-applied mulch containing heat-treated wood
fibers, cross-linking tackifiers, and man-made fibers, which allows them to bond mechanically
with the soil surface.
Floc -----Agglomerated colloidal particles.
Flocculant -----A chemical added to turbid water to accelerate the formation of clumps from finegrained
particles suspended in the water for the purpose of settling-out those particles prior to
discharging into surface waters.
Flocculation -----The agglomeration of finely divided suspended solids into larger, usually gelatinous,
particles.
Flood -----A general but temporary condition of partial or complete inundation of normally dry land
areas from the overflow of streams, rivers, or other surface waters.
Flood Control -----Preventing the entry of stormwater into an area from another area, or from a stream
or other water body.
Flood Peak -----The highest stage — greatest discharge rate — attained by a flood event.
Flood Prone Soil -----Soil susceptible to flooding during a 2-year frequency storm event.
Flood Routing -----An analytical technique used to compute the effects of system storage and system
dynamics on the shape and movement of a flood wave.
Flood Stage -----The stage at which overflow of the natural banks of a stream begins.
Floodgate -----A gate placed in a channel or closed conduit to keep out floodwater or tidal backwater.
Flooding (Soil) -----Any soil subject to inundation during a 2-year/24 hour storm event.
Floodplain -----The land adjacent to a river or stream that has been, or could be, expected to be
inundated by a flood resulting from a 100-year storm event.
Floodwall -----A flood barrier constructed of manmade materials, such as concrete or masonry.
Floodway -----The area of the floodplain required to carry the discharge from a 100-year storm event.
Where no FEMA mapping has been completed, it is assumed to be 50’ back from top of bank.
Flow Length -----The distance that runoff travels to or through a BMP.
Flow Line -----The bottom elevation of an open or closed conduit.
Flow Path -----The anticipated course that runoff will follow during a storm event.
Flow Regime -----1. In runoff calculations: overland, shallow concentrated, or channel flow. 2. In
channel stability calculations: subcritical, critical, or supercritical flow. 3. In culvert capacity
calculations: entrance control or exit control.
363-2134-008 / March 31, 2012 / Page 519