Erosion and Sediment Pollution Control Program Manual.pdf

Grade -----1. The slope of a road or trail expressed as a percent change in elevation per unit of
distance traveled. 2. The finished surface of a roadbed, utility trench, fill, or excavation.
Grade Stabilization Structure -----See Drop Structure.
Graded Stream -----A natural channel that has achieved the necessary flow characteristics for
transporting the amount of sediment supplied by its drainage basin.
Grading -----Changing the shape of the land’s surface to facilitate building, transportation, or other
human activity.
Gradient -----Change in elevation, velocity, pressure, or other measurable characteristic per unit length,
slope.
Grain -----A unit of weight equal to 1/7,000 pound or 0.0648 gram.
Grassed Waterway -----A natural or constructed waterway, typically broad and shallow, covered with
an erosion-resistant grass.
Grate -----A metal frame of parallel bars placed in the entrance to a storm sewer inlet to prevent debris,
animals, etc. from entering the sewer line.
Gravel -----1. Soil particles ranging from 1/5” (2 mm) to 3” (7.6 cm) in diameter. 2. The material retained
on a No. 4 sieve.
Gravel Bars -----Alluvial deposits in stream channels, including accumulations of gravel, glacial till,
sediment, silt and flood debris, that obstruct and redirect flow, and are thereby associated with
stream bank erosion.
Gravitational Water -----Free water in transit downward through the vadose, or unsaturated, zone.
Greenbelt -----A strip of trees and/or shrubs growing parallel to a stream preventing overuse of the top
bank area by people, animals, and machinery. It retards rainfall runoff down the bank slope and
provides a root system that helps to bind soil particles together. Also called a greenway.
Groin -----1. The intersection between a fill and natural ground. 2. A shore protection structure, usually
perpendicular to the shoreline, built to trap shoreline drift material or to retard erosion of the
shore.
Groin Ditch -----A stabilized channel running down-slope parallel to a right-of-way or to the edge of a
fill to safely convey runoff to a desired point of discharge.
Grooving -----A method of roughening a cut or fill slope in order to reduce the potential for gully
formation on the slope until a suitable vegetative cover can be established.
Groundcover -----Low-growing, herbaceous or woody plants that spread vegetatively to produce a
dense, continuous cover.
Groundwater -----Water found below the surface of the land, usually in permeable rock formations. It
is the source of water for wells and springs.
Groundwater Flow -----Water moving through the subsurface soil and rock.
Groundwater Infiltration -----The seepage of groundwater into a sewer line.
Groundwater Runoff -----The seepage of groundwater into a stream channel.
Groundwater Table -----The depth below the surface where the soil or rock is saturated, such as open
spaces between individual particles filled with water.
Grout -----A fluid mixture of cement, water and sand or other fillers that can be poured or pumped
easily. Used to fill voids in riprap, culverts, or other structures in channels or slopes, intended to
prevent or reduce erosion or inadvertent water flow.
Grout Curtain (Grout Cutoff) -----A barrier produced by injecting grout into a vertical zone, usually
narrow horizontally, in the foundation of a dam to reduce seepage under the dam.
Grouted Riprap -----Riprap that has been coated with a specialized type of concrete that is designed to
fill voids and reduce the potential for movement of the stone during high flow/high velocity
conditions. This is generally accomplished by placing the riprap on a layer of grout, then
covering with another layer of grout.
Growing Season -----The season that, in general, is warm enough for the growth of plants 1. Time
from the last killing frost of spring to the first killing frost in autumn. 2 That period of the year
when the daily mean temperatures are above 42 O F.
Grubbing -----The operation of removing stumps and roots.
Gully -----An erosion channel too large to cross with a wheeled vehicle.
Gully Erosion -----An advanced form of rill erosion, in which large channels are incised into the soil by
water runoff.
363-2134-008 / March 31, 2012 / Page 523