LARE 4 Flashcards
Stormwater wet pond design
Use organic geometries
include topographic variation
Maintain a depth of 4-8’
Increasing flow length (distance water travels downstream)
Lawn or grass area maximum slope
25%
Burrow Pit Method
Used for calculating cut/fill in complex grading projects;
Involves a grid across the site, assigning an elevation to each point; spacing of grid contributes to accuracy
Standard sections in a technical specification
General - basic scope of work
Product - specific materials and manufacturing or fabrication processes
Execution - actual means of preparing, installing or constructing, and quality or performance requirements
AASHTO
American Association of State Highway and transportation Officials - creates standards for public roadway construction
NFPA
National Fire Protection Association
ACI
American Concrete institution
CSI
Construction Specifications Institute (creates master format)
Master Format
01 - Gen Requirements 02- Existing Conditions 03- Concrete 04- Masonry 05- Metals 06- Wood, plastics, composites 07- Moisture/thermal protection 08- Openings 09- Finishes 10- Specialties 11 - Equipment 12 -Furnishings 31 - Earthwork
Strategies for improving site safety
Improve visibility Design for natural surveillance promote positive image of site multiple access points perceived ownership of site
Observation well
Slotted or screened tube or pipe in an infiltration trench to allow operator to check conditions
Recharge trench
placed downhill of a vegetated filter strip; linear trench filled with gravel, lined with filter fabric, including sand filter or filter fabric
Snap ties
used to hold formwork together while concrete is being poured; designed to break away after formwork is removed; can remain inside concrete to provide reinforcement
Level spreader
distributes stormwater over a wide area
Filter strips
filter sediments from stormwater, improve water quality, treat sheet flows
How to rehabilitate compacted soils
determine if compaction is located in surface or subsoil; amend soils with organic matter
Asphalt treated base
used in construction in wet or freezing conditions; prevents infiltration into fines of subgrade; 3x as strong as untreated base (crushed rock) so base layer can be 1/3 the depth
Invert elevation of a pipe
the distance between the bottom of the interior of the pipe and the surface of the ground.
Bioengineering
using plant material (such as live stakes) to restore eroded stream banks and stabilize soils, reducing sediment deposition and erosion in waterways
countersinking
having a conical hole so a bolt or screw top is flush with the material surface
Ledger
component of a deck - a board that supports joists and transfers loads from deck to structure to which it is attached
Site protection plan
protects natural resources on a site, sensitive areas on or adjacent and downstream or site, and complies with local laws and codes; includes tree protection, materials salvage, site access, erosion control and noise control
Connected imperviousness
Runoff drains directly from impervious surfaces to drainageways
Disconnected imperviousness
Runoff drains from impervious surfaces to previous like grass, resulting in more infiltration and better water quality
Ideal buffer around urban streams
25 ft undisturbed forest, plus 50-100 feet of managed vegetated area
Schematic design for stormwater key points
Slow runoff velocities to pre development conditions
Try to remove impervious surfaces from drainage pathways
Place development away from drainage ways, step slopes, complex plant communities and porous soils
Factors that effect stormwater velocity
Surface friction, surface shape, slope
Best place for impervious surfaces and pavement in stormwater design
High points, like along ridges
Type of storm that major anf minor flood protection systems are designed for
100 year, 24 hour design storm - major system
2, 5 or 10 year 1 hour design storm - minor system
ADA hand rail height
34-38”
Guard rail heigh
42” minimum
Surface albedo
measure of the diffuse reflection of solar radiation off a surface; black surfaces have albedo of 0; a surface that reflects all radiation would have an albedo of 1
Cribbing
walls placed in a series perpendicular to water flow to intercept stormwater running down a slope and trap sediment.
Benefits of compost blankets
Reduces soil erosion on slopes (usually up to 2:1), slows flow of stormwater, reduces peak flow, traps moisture and protects seeds to stimulate plant growth, reduces sediment and nutrients in stormwater, stimulates microbial activity which increases organic matter in soil and improved soil structure
Hydrograph
a graph showing the rate of flow versus time past a specific point in a river or stormwater system, usually expressed in cubic feet per second
Discharge
Rate if runoff flow, volume traveling at a particular velocity, expressed in cubic feet or cubic meters per second. Equal to velocity times area of flow
Volume of flow
Discharge times length of time, expressed in cubic feet or acre feet
Hydrograph
Summary of stormwater flows, record of flow rates at a particular location over a given time. Can be a tabular form or a graph plot (discharge vs. Time). The area under the plotted curve is the total volume of flow for the plot period.
Peak rate of flow
Top of the hydrograph, occurs when flow consists of one drop of water from every point in the watershed
Minor stormwater system
Designed to reduce inconvenience of 2, 5 or 10 year storms. Includes storm sewers and roadside swales. Maybe designed using rational method (storm sewrs) or SCS runoff method (overland systems)
Major stormwayer system
Pay that runoff takes when minor system is overwhelmed. May be designed or natural. Examples are emergency spillways, and floodwaters. Designed for 100 year storm, typically using SCS runoff method.
Time to concentration
Time water takes to flow from the most distant point in a watershed to its outlet
Isohyetal map
Maps of design rainfall depths for the entire US produced in 1961
Steel formula
Method for calculating rainfall intensity from the design storm and region of the US, used with the rational method
Manning Kinematic Solution
Formula used to calculate sheet flow
SCS runoff curve number method
Used for radials between 1 and 12”
Watersheds under 20 sq miles
In wood construction, a short part loaded to failure will…
Crush
A beam subjected to compressive force will exhibit tensile stress once the forces pass through the…
Neutral axis
A beam subjected to compressive force will exhibit tensile stress once the forces pass through the…
Neutral axis
Bituminous surface treatment
Or chip seal. Aggregate in asphalt binder used to reseal asphalt concrete pavement or to page low traffic roads.
Bituminous surface treatment
Or chip seal. Aggregate in asphalt binder used to reseal asphalt concrete pavement or to page low traffic roads.
To remain durable all layers of asphalt pavement must be….
Compacted
How much does a cubic for of concrete weigh?
150 lbs
Number of reinforcing bars refers to diameter in what unit?
Eighth inches
Purpose of welded mesh wire in concrete is to..
Reduce cracking
What is used to reduce displacement in concrete slabs?
Doweled joints
How far apart can expansion joints be in concrete slabs?
2-3 times in feet the depth of the slab in inches
Reaction when external force is applied to an element causing it to bend
Bending moment
Gravity retaining wall
Rely on mass to resist pressure and may lean back toward retained soil. Small walls may not require mortar or a footing
Crib wall
Made of cells built log cabin style from pre ast concrete or timber filled with granular material
Gabion
Steal basket filled with rocks
Cantilevered retaining wall
Made of reinforced cast in place concrete, or mortared masonry, shaped like an inverted T. Transfers horizontal pressure to vertical pressure.
Counterforted retaining wall
A cantilevered wall with buttresses on the back of the wall.
Horizontal force of soil against retaining walls
Lateral earth pressure
Ingredients of brick border
Sand, cement, water, lime
Efflorescence
Migration of salt to the surface of a porous material
The types of retaining wall failure
Sliding, buckling, overturning
What does a key in a retaining wall footing do?
Increases footing bearing area
Board foot
Measure of volume of a board, equal to a board that is 1foot wide, 1 foot long and 1 inch thick
Lag bolt
Larger head than normal screw, can support heavier load
Azimuth
Angle from north, measured clockwise, north is 0 degrees, south is 180 degrees
Townships
36 square miles, measured on lines called baselines and meridians
Stadia method
Measures horizontal distance from the trains of a stadia rod, with the formula
Distance = (difference in stadia readings) x K + C K = constant that is usually 100 C = usually zero
Plane surveying
Determines elevations from a benchmark and a survey instrument placed between the benchmark elevation and the unknown elevation.
Backsight is the reading from the instrument to the benchmark. Foresight is the measurement to the unknown elevation.
Lux
Measure of light intensity within a specific area, or light cast on a surface. Equal to lumens per square meter.
Lumen
Total visible light emitted from a light source.
Watts vs amps vs voltss
Watts = amps x volts
Amps is like volume of electric current
Volts is speed at which electric current passes a point
Watts is the power that is generated
ASTM soil classification system groups soils according to …
Bearing capacity
Tack coat
Emulsified asphalt used to bond two asphalt courses
Wythe
A continuous vertical section of masonry that is one unit thickness
Concrete block wall design
Depth to bottom off footing should be minimum of 2 feet, and below the frost line
Length of footing should be 50% total wall height (including height of footing)
Control joints
Prevent cracking due to contraction/shrinkage
Minimum wheelchair clearance width
36”
Stadia method
D = 100 x difference in stadia readings + constant (usually 0)
Rational method formula
Q = KCiA
Used to calculate peak discharge of runoff on urban areas.
Q peak discharge of runoff in square feet per second
K constant (1 in US units)
C runoff coefficient (runoff/rainfall)
I rainfall intensity at time of concentration (calculated using steel formula)
A watershed area in acres
Manning formula
Calculates water flow through conveyance structures (pipes, swales)
Q = VA
Q = discharge in cubic feet/second V = velocity A = area of cross section of water flow
Hydrlologic Soil groups and runoff production
Type A is most pervious
Type D is least pervious (most clay content) and produces most runoff
Calculation for wetted perimeter in channel flow
R = A/P
R= hydraulic radius (in feet) A= cross sectional area in square feet P= wetted perimeter
Sheet flow is most likely to occur in..
Uppermost headwater area of a watershed
Minimum width for handicap parking stall
12’
Soil structure
Arrangement of the solid parts of soil and the space between them major types are platy, prismatic, columnar, granular, blocky
Nutrients in fertilizer
Nitrogen, phosphorus, potassium
NPK
10-20-20 represents percentage by weight of each nutrient
Adding sulfur to soil is used to…
Increase soil acidity
Space required for tennis courts
120’ x 60’
Actual court dimensions are 78’ x 36’
Footcandle
One lumen per square foot
Footcandle
One lumen per square foot
Average end area formula
Sections are cut through a site and their square footage of cut and fill are calculated
Concrete cement weight per cubic foot
150 lbs
Concrete cement weight per cubic foot
150 lbs
Natural gas lines cannot be placed kn the same trench as
Electric or telephone lines
Refusal in soil engineering
Point when a pile cannot be driven farther into the ground (hard soil or rock is encountered)
Refusal in soil engineering
Point when a pile cannot be driven farther into the ground (hard soil or rock is encountered)
Sprinklee heads should be spaced..
The radius of the throw
Land subsidence
Sinking or settling of land, often because groundwater is depleted
