Erosion and Sediment Pollution Control Program Manual.pdf

earth disturbance activity on any portion, part, or during any stage of, a larger common plan of
development or sale that involves 1 acre (0.4 hectares) or more of earth disturbance activity
over the life of the project.
NRCS -----Natural Resources Conservation Service, formerly known as SCS, a federal agency under
the U.S. Department of Agriculture which, among other things, provides technical assistance to
conservation districts, assists farmers in developing conservation plans, provides soil survey
information, and assists local governments in planning and installation of erosion and flood
control projects.
NRDC -----Natural Resources Defense Council, a private American environmental organization
emphasizing the proper management of natural resources.
Nutrients -----1. Mineral elements, such as nitrogen, phosphorus, or potassium, that are necessary for
the growth and reproduction of organisms. 2. In water, those substances that promote growth
of algae and bacteria, chiefly nitrates and phosphates.
Nutrient Management -----Proper use of control measures and BMPs during to application of soil
amendments to agricultural lands so that the soil amendments are not carried by runoff into
surface waters.
NWI -----National Wetlands Inventory.
NWP -----Federal Nationwide Permit.
NWS -----National Weather Service.
O
Obligate Hydrophytes -----Plant species found only in wetlands.
Observation Well -----A non-pumping well used to observe the elevation of the water table or the
potentiometric surface. It is usually larger diameter than a piezometer and is typically screened
or slotted throughout the thickness of the aquifer.
Obstruction -----Any structure or material in, along, across, or projecting into any watercourse that may
alter, impede, retard or change the direction and/or velocity of the flow of water, or due to its
location, its propensity to snare or collect debris carried by the flow, or its likelihood of being
carried downstream.
Ogee -----A reverse curve shaped like an elongated letter S. The downstream faces of overflow dams
are often made in this shape.
Oil and Gas Activities -----Earth disturbance associated with oil and gas exploration, production,
processing, or treatment operations or transmission facilities.
Oligotrophic -----Nutrient-poor.
On-Lot Controls -----BMPs used during construction of the individual buildings of a housing project,
industrial park, etc. They typically consist of a stabilized access, sediment barrier(s), and
diversion channels — were necessary. On-lot controls should not be substituted for perimeter
BMPs such as sediment basins and/or traps.
On-lot Sewage System -----A community and/or individual sewage system that uses a system of
piping, tanks, or other facilities of r collecting, treating and disposing of sewage into a
subsurface absorption area or a retaining tank.
1-Hour Storm -----A storm event having a duration of 1 hour.
100-Year Flood -----A flood having a one-percent chance of being equaled or exceeded in any given
year.
Open Channel -----A natural or manmade structure that conveys water with the top surface in contact
with the atmosphere.
Open Channel Flow -----Flow in an open conduit or channel that is driven by gravitational forces.
Open Drain ----- A natural watercourse or constructed open channel that conveys drainage water.
Operator -----A person who has one or more of the following: 1) Oversight responsibility of earth
disturbance activity on a project site or a portion thereof who has the ability to make
modifications to the E&S Plan, PCSM Plan or site specifications. 2) Day-to-day operational
control over earth disturbance activity on all or part of a project site or a portion thereof to
ensure compliance with the E&S Plan or PCSM.
363-2134-008 / March 31, 2012 / Page 534