Flashcards in CPESC Deck (120):
Years of Federal Water Pollution Control Act and three CWA amendments
1948, 1972, 1977, 1987
Year NPDES came into being
1972 amendment to FWPCA
Types of controls emphasized within NPDES program
The name of a series of studies and projects funded by EPA from 1978 through 1983
Nationwide Urban Runoff Program
When permits for storm water discharges came into being; CWA section; the term for these entities
1987 amendments to CWA402(p)Phase 1
when industrial and construction baseline general permits" were first issued"
When EPA issued a final rule for Phase II's; when they had to submit applications by
Groups included in Phase II""
- light industrial facilities- small construction sites- municipalities < 100k
Coastal Zone Act Reauthorization Amendments
1990--required the development of a Coastal Nonpoint Pollution Control Program Management Plan for every designated state under coastal zone jurisdiction.
Uncontrolled construciton site sediment loads exceed ______ of ______ per year
hundreds of tons per year
Stormwater is defnied under EPA's NPDES rules as:
stomwater runoff, snow melt runoff, and surface runoff and drainage
stormwater discharges does not include
return flows from irrigated agriculture or agricultrual stormwater runoff
The definition of waters of the united states" includes the following (7)"
1. All waters that are currently used, were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters that are subject to the ebb and flow of the tide;2. All interstate waters, including interstate wetlands;3. All other waters such as intrastate lakes, river, streams (including intermitten streams), mudflats, sandflats. wetlands
wetlands are those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal conditions do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas
THe six minimum control measures
1. Public edu and outreach2. Public participation/involvement3. Illicit discharge detection and elimination4. Construction site runoff control5. Post-construction runoff control6. Pollution prevention/good housekeeping
the applicable standards for Phase II municipalities are to
reduce the discharge of pollutants to the MEP, protect water quality, and satisfy the water quality requirements of the CWA
fundamental purpose of the CWA
to protect the BUs of surface waters
What does the CWA requires States to do?
Adopt water quality standards
The TMDL process has three steps:
1. ID quality-limited waters2. Establish priority waters/watersheds3. Develop TMDLs
What do water quality standards do?
define the goals for a waterbody by designating its uses, setting criteria to protect those uses, and establishing provisions such as antidegradation policies to protect waterbodies from pollutants.
How does a state identify quality limited waters?
303(d) list of waters that do not or are expected not to meet WQS after applying existing required controls
What does a TMDL define?
The amount of a particular pollutant that a water body can assimilate on a daily basis without violating applicable water quality standards
TMDLs should address all significant contributors that cause or threaten to cause water body use impairment, including (3):
TMDL plans may address individual pollutants or groups of pollutants, as long as they clearly identify the links between:
Federal NTU limitation and storm limit
280 NTU2-year, 24-hour storm, then no limit
When the EPA issued the final rule for effluent limitation guidelines---when became effective
All three general permits share the following conditions:
Those facilities that are required to apply for individual permits for their sw dischargers are:
2 application methods for obtaining an NPDES permit for sw discharges
The NOI should include the following info:
EPA offers three general permits:
Site evaluation and design development
6 major phases of SWPP planning for construction activities:
1. Site evaluation and design development2. Project Assessment3. Control selection and plan design4. Certification and notification5. Construction/implementation6. Final stabilization/termination
Info to obtain when collecting site info (4)
The SWPP site plan map should include (4)
- location of surface waters- location and steepness of slopes after grading- location and area of soil disturbing activities- Drainage patterns all stages, runon and runoff
What is involved in SWPPP project assessment?
EPA GP and sediment basins
Basin be installed where 10 acre+ of upstream drainage area is disturbed at one time. Must provide 3,600 ft^3 for every acre of land drained
EPA's construction permit requires inspection every ___ days or within _______
7 days24 hours of a storm of 0.5 inches or more in depth
Releases of reportable quantities of hazardous substances during construction must be reported in the following manner:
- Notify the National Response Center in D.C., immediately- Submit a written description of the release to EPA regional office within 14 days, including date, circumstance, control measures- Modify SWPPP as app
EPA has authority to bring 3 types of enfocement actions:
What EPA can accomplish with a civil action
The applicable standards for Phase II muni's are to ______, __, and ______
reduce the discharge of pollutants to the MEP, protect water quality, and satisfy the CWA
The erosion potential of a site is determined by these five factors:
Contour interval on SWPPP plans should be
2 feet or less
The USLE should be limited to situations in which _______
It's factors can be accurately evaluated and the conditions for it can be reliably applied
RUSL equation formula
A = R x K x L x S x C x P
The USLE represents soil erosion as a product of these six factors:
Rainfall and runoff erosivenessSoil erodibilitySlope lengthSlope steepnessCover-management practicesSupport conservation practices
RUSLE Equation, A""
A = Spatial avg soil loss and temporal avg. soil loss per unit of area, expressed in the units selected for K and for the period, R.
RUSLE Equation, A
is usually expressed in what units?
RUSLE Equation, R""
Rainfall-runoff erosivity factorthe rainfall erosion index plus a factor for any significant runoff from snowmelt
RUSLE Equation, K""
Soil erodibility factorthe soil loss rate per erosion index unit for a specified soil
RUSLE Equation, L""
Slope length factorthe ratio of soil loss fron the field slope length to soil loss from a 72.6 ft length under identical conditions- Erosion increases as slope length increases
RUSLE Equation, S""
Slope-steepness factorThe ratio of soil loss from the field slope gradient to soil loss from a 9% slope under otherwise identical conditions
RUSLE Equation, C""
Cover-management factorthe ratio of soil loss from an area with specified cover and management to soil loss from an identical area in a bare condition
RUSLE Equation, P""
erosion control practice factorthe ratio of soil loss with certain conservation practice to that of no practice
Numerical values for each of the six RUSLE factors were derived from analysis of research data and from _____
NWS precipitation records
What is the RUSLE?
An erosion model designed to predict the longtime average annual soil loss (A) carried by runoff from specific slopes in specified management conditions
better at predicting long-term averages than prediction of specific events
Component of the RUSLE that would address the effects of compaction on erosion
cover-management factor C""
from disturbed landsComponent of the RUSLE that would address slope steepness effects on soil loss
Limitation to consider with respect to A""
A is the avg. loss over a slope and looses at various parts of the slope may differ greatly from one area to another
RUSLE factor that accounts for influence of soil properties on soil loss during storm events on upland areas
soil-erodibility factor (K)
two things that must be reflected in the calculation of R""
Erosion forces not reflected in the Wischmeier erosion index (R) tables
A basic way to think of soil erodibility (K)
the ease with which soil is detached by splash during rainfall or by surface flow, or both
Soil A" layer"
- Upper part of the natural horizon; the topsoil.- Dark in color and generally 0-10 inches thick
Soil B" layer"
- Subsoil between the A layer and the parent material- 26-60 inches thick
Soil C" layer"
- Upper part of the parent material.- 26-60 inches thick
Soil information required to use the nomographs
RUSLE--accounts for the effect of topography on erosion
LS factor, aka the topographic factor
Definition of slope length
The horizontal distance from the origin of overland flow to the point where either:1. The slope gradient decreases enough that deposition begins; or2. Runoff becomes concentrated in a defined channel
Surface runoff will usually concentrate in less than ___ feet
Slopes as long as ____ feet should not be used in the RUSLE equation
Determining steep slope lengths for use in RUSLE
Use the horizontal distance, where slope is hypotenuse, c, and slope length is b, which ends on the downhill end where deposition begins
2 factors that substantially affect sheet and rill erosion estimated by the RUSLE
slope length and steepness
pH of pure water
2 RUSLE factors that are usually evaluated together
LS (length and steepness)
Equation for slope-length factor (L)
L= (λ72.6)m72.6= RUSLE plot length (ft)λ=Horizontal projection slope lengthm= variable slope-length exponent
Cause of Rill and Inter-Rill erosion
Rill: FlowInter-rill: Raindrop
Sediment Basin Design Equation
As = 1.2 Q/Vs As = Minimum surface area for trapping soil particles of certain sizeVs = Settling velocity of the design particle size chosenQ = Discharge rate measured in cubic feet per second
How should the variable slope-length exponent (m) be changed when conditions favor less rill erosion than inter-rill erosion?
How should the variable slope-length exponent (m) be changed when runoff, soil, cover, and management conditions indicate that the soil is highly susceptible to rill erosion? Where would this occur?
- m should be increased. Double the β value before applying m= equation- Steep, freshly prepared construction slopes
Check dam ratio relationship
ratio relation between the swales drop and length and the height and spacing of the check damsdrop/ length=check dam height/check dam distance
How is the slope length exponent affected when deposition occurs between ridged and in depressions?Why?
-exponent should be 0-Soil loss is independent of slope length
slope length exponent m, when surface flow, alone, causes erosion of thawing soil
m is a constant value of 0.5
Describes the settling velocity of particles in a body of water
what equation uses m
the slope length exponent?
What does the slope-steepness factor (s) reflect?
The influence of slope gradient on erosion
Soil loss increases more with slope ______ than with slope ________
X:Y slopes--the 1" is always the ______ value"
- Slope steepness angle threshold that determines which slope steepness factor equation is used- What is significant about this threshold?- When can these 2 equations be used?
- 9%- Runoff is not a function of slope steepness after 9%- Slopes greater than 15 feet in length
A separate slope steepness factor (S) equation should be used when slopes are shorter than ____ feet
How is slope steepness estimated in the field?In the office?
- clinometer, Abney level, or similar device- Contour maps with 2-foot contour intervals
LS values are not absolute values, but represent the ratio of soil loss relative to...
a slope 72.6 feet long with a 9% steepness, where all other conditions are the same
RUSLE factor that involves the most judgement
What does the C-factor indicate?
How the cover management practices will affect the average annual soil loss and how that soil loss potential will be distributed in time during construction activities
Rill erosion is assumed to begin with a slope length of ____ feet
15, but could occur sooner on susceptible slopes
What is the soil loss ratio?""
An estimate of the ratio of soil loss under actual conditions to losses experienced under the reference conditions
check dams3 main factors
slope %distance between damsheight of dams
Calculating roughness factor
Real Surface Area\geometric surface area (2D)
V" in modilied universal soil loss equasion"
volume of runoff due to the storm event, in acre feet
Qp" in modilied universal soil loss equasion"
peak flow for the storm evebt , in CFS
Equation used if you want to figure soil loss per event
time of concentration
the time it takes runoff to travel from the hydraulically most distant point in the watershed to the design point
How is the Tc computed?
summing all the travel times for consecutive components in the conveyance system
When does shallow concentrated flow occur?
Once flow begins to form rills
When will shallow concentrated flow begin to occur?
Within 150 feet of the onset of runoff, and seldom after 300 feet of sheetflow
What is Initial Abstraction?What does it include?
the sum of the losses that occur before runoff begins.Includes intercetption, evaporation, and infiltration
Peak Discharge Equation for a Rainfall EVENT
QP=QU X A X Q X FPQU=UNIT PEAK DISCHARGEA=the watershed areaQ=runoff in watershed inchesFp=adjustment for watershed storage(pond, swamp)
Pure Live Seed
germination x purity
X=Rainfall, inchesY=Direct Runoff, Inches
Mulch with best micro-environment for germinating seeds
Use what kind of mulch where mulch is maintained for more than three months?
What do temporary mulches do
Temp E/CEstablish vegetation
How do mulches function
mulch fibers joined by adhesivesporous blanket
3 types of soil stabilzer applications
- Alone as bare earth" e/c- Sprayed over fibres
4 types of RECP
1. Mulch Control Netting2. Open Weave textile3. Erosion control blanket4. Turf reinforcement mat
Silt fence rule of thumb
1/4 acre per 100 feet of fence buried 6-8 inches