Design Flashcards
Area Drain
structure similar to a floor drain that collects runoff from paved areas. Usually one is used for each 1,000-2,000 square feet of pavement.
Asphalt - General Conditions
Under general conditions, properly constructed asphalt pavement requires surface maintenance or resurfacing every 20 years under typical operating conditions.
Asphalt - Adhering a New Coat to an existing Asphalt surface
A bituminous binder would be used to adhere a new coat of asphalt to an existing asphalt surface.
Asphalt - Asphalt Treated Base
Asphalt treated base is an alternative to untreated base material and is typically used during construction in wet or freezing conditions.
ATB acts as a water-resistant barrier that prevents the infiltration of fines into the subgrade, which occurs when water accumulates in the subgrade. Not only does this clog the base layer (thereby impeding drainage), it can also create voids in the subgrade into which the pavement may settle.
It should also be noted that ATB is about three times as strong as an untreated granular base (such as crushed rock). Therefore, it is possible to use thinner layers for the same structural support, which can save on excavation costs.
Architectural Grid System
An architectural grid system utilizes the proposed building grid (established by the architect) to organize and lay out elements of the proposed site construction. It can be used to locate specific site elements on a Site Layout Plan.
Albedo
Reflection of light off of a surface like Asphalt or Concrete. A perfect reflector would have an albedo of 1, whereas a perfect absorber would have an albedo of 0.
ADA, Handrails
ADA-compliant handrails are required to be anywhere from 34”-38” in height.
Clear of obstructions on top and sides by a min. of 1.5”.
Handrail itself is 1 1/4”-2” in diameter if circular or to provide an equivalent gripping surface
Non-circular to have a perimeter dimension of 4 inches to 6 ¼ inches, and a cross section dimension of 2 ¼ inches maximum.
It must extend 12” horizontally beyond the top and bottom of the ramp/step and return to the wall or handrail itself.
Handrail gripping surfaces to be continuous, and to be uninterrupted by newel posts, other construction elements, or obstructions.
ADA, Table Height
Tables should be located anywhere between 28” - 34” to comply with current best practices. And should have 27” clearance at the bottom of the table (can be 24” for children specific tables).
ADA - Ramps
Typical slope ratios range from 1:20 (5%) to 1:12 (8.3%) for pedestrian use. 1:20 or greater require a handrail if ramp is more than 6” of vertical rise (i.e. more than a curb ramp which doesn’t require handrails). Where ramps exceed 30 ft. in length, an intermediate landing (min. 60” long) is required. If the ramp changes direction, then the landing must be 60”x60” min. Per ADA the max rise for ramps from 1:12 to 1:16 must not exceed 30 in. and an intermediate landing must be provided at least every 30 ft. For slopes ranging between 1:16 and 1:20, the maximum rise cannot exceed 30 in. and a landing must be provided every 40 ft. Cross pitch must not exceed 1:50 (2%).
ADA- Parking
Space minimum 8’ wide with 5’ min access aisle. 98” is the vertical clearance for van accessible space (parking garage, etc.) Cross slope no more than 1:48 (~2%). Sign should be 60” above grade (top of sidewalk if sitting on sidewalk in front of parking space).
ADA - Accessible Routes
Min. 36” wide, but can be as narrow as 32” for no more than 24” along the path and those pinches in the route can happen no closer than 48” apart.
If the route is greater than 200’ long, then there must be a 60”x60” min passing space along the route. Running slope no steeper than 1:20 (5%) with cross slope no greater than 1:48 (~2%).
ADA - Curb Ramps
Min. 36” wide, with 1:12 (8.3%) running slope and cross slope no greater than 1:48 (~2%). If there is a landing area at the top, then it must be at least 36” in length, then the flares at the sides are to be no steeper than 1:10 (10%). However, if there isn’t a landing at the top then the flares need to be like ramps (i.e. 1:12).
Abbreviations - AASHTO
American Association of State Highway and Transportation Officials
Abbreviations - NFPA
National Fire Protection Association
Abbreviations - CSI
Construction Specifications Institute
Abbreviations - ACI
American Concrete Institute
Bituminous Paving
Asphalt is made up of bituminous material. Bitumen is the residue or by-product when the crude petroleum is refined.
Bioretention Systems (Bioretention Swales)
Vegetated swales provide an alternative to curbs and gutters. The addition of plants results in an increase of friction slowing the flow of water and increased times of concentration.
Bioretention Systems (Bioretention Cells or Rain Gardens)
An informal infiltration basin often with an organic layout, that has good soil drainage, is ideally located in existing low-lying areas and away from building foundations and septic systems. It should also receive full to at least partial sun to maximize evaporation. The top 18” of soil should consist of native soil amended with compost and sand both to allow good infiltration rates and provide fertile soil that will allow plants in the rain garden to thrive.
Beam - Compressive Force and Tensile Stress
A beam (a horizontal member) goes through both compressive force and tensile stress due to the way a load is placed on it. When a beam is subject to compressive force, it will exhibit tensile stress once the force passes through the Neutral Axis. Think of a sponge, bend it in half and the bottom will get compressed while the top is stretching out (pulling) which is tensile stress, so it is going through both compressive force and tensile stress at the same time.
Beam - Applied Load
A beam subject to an applied load along its length will exhibit a Moment (see Moment of Force).
Conversions - Square Inches to Square Feet
You need to divide by 144 (it’s square so 12” x 12” = 144”)
Catch Basin
A structure typically out of concrete with an opening that is 2.5’-4’, used to collect and divert surface runoff to an underground conduction system. General rule of thumb is that one catch basin may be used for each 10,000 square feet of paved surface.
Cistern for Rainwater Harvesting Systems (Irrigation)
A rule of thumb is 1” of water per week is needed for irrigation systems. If you are designing a cistern to allow for a 3 week dry spell (differs based on location) you would need to store 3” of water multiplied by the total planted area of the site. If you had say 2,500 sq.ft. of planting then 2,500 * 0.25’ (3” converted) = 625 cu.ft. of water. To convert that to gallons 1 cu.ft. ~ 7.48 gal of water. So 625 * 7.48 = 4,675 gal is the minimum size cistern you would need.
Cistern for Rainwater Harvesting Systems (Catching Enough Rain to meet the above example)
Though a 4,675 gal cistern is needed in the above example, that doesn’t mean that enough rain falls to fill that cistern prior to the 3 week dry period. Besides that, there is also an inherent inefficiency to all of these systems for water lost to evaporation, first flush of the system, etc. and this is typically assumed to be 75%-90%. So if you have a roof top that is 1,000 sq.ft. in area (doesn’t matter if it is flat or sloped, you take the plan view area of the roof) and say a 75% efficiency, that means that 1,000 * 0.75 = 750 sq.ft. of water being stored at 1” depth. So this needs to be converted to cu.ft. so 750 / 12 = 62.5 cu.ft. and finally convert to gallons so 62.5 cu.ft * 7.48 = 467.5 gallons (again that is per 1” of rainwater fallen). So in order to fill the above cistern, we would need 10” of rain to fall (4,675 / 467.5 = 10”).
Cistern for Rainwater Harvesting (Parts of the System)
The cistern itself of course, a distribution system, a filter (to get rid of large debris) and a catchment area.
Cordonata
The arrangement of stairs with ramps so that you have 1 step up and then a long ramped section, then another single step up, and another ramped section, etc. This is uncomfortable to walk on as the stride up the steps is constantly interrupted by the single steps and the slope is more noticeable between steps.
Culvert
Any structure, NOT classified as a bridge, that allows water to flow beneath a road, walk, or highway.
CUT AND FILL
NOTE: The below cut and fill methods are from LAGS starting on page 196. See that section for pictures/examples. Also info available at this website https://www.kublasoftware.com/how-to-calculate-cut-and-fill/
Cut and Fill (Average End Area Method)
This method is good for figuring out earthwork in construction of linear objects. To start, in plan view, draw a centerline through your path (walkway, driveway, road, etc.) This centerline is the peak of your path (dirt mounds up to it). Next take evenly located points along that path (station points, etc.) At those points cut a cross section and look at the section through the mound on a graph. Find the area of that section (if not given, cut into trapezoids and find the area of each one to get a rough total. Do the same for the next cross section at the next station point. Finally, figure out the fill in the area between them by adding both areas together, dividing that value by 2 (i.e. get the average, if it was 3 stations then you would add all three and divide by 3, etc.) and then multiply by the distance between sections to get cubic feet. Remember to divide that by 27 to convert to cubic yards if asked.
Cut and Fill (Grid Method a.k.a. “borrow pit method”)
This method is good for excavations. Start by overlaying, in plan view, squares over the area of work. Then for each square calculate the depth of each corner from existing grade. Find the average of the 4 resulting depths (add all 4 depths and divide that answer by 4). Next multiply this average depth by the area of the square and this will give the Volume in cubic feet. Remember to divide that by 27 to convert to cubic yards if asked.
Grid Method - Quick Formula for more than 1 square
If you have to figure out the area of excavation of more than 1 square (e.g. 5 squares) you can apply the formula V = [(a+2b+3c+4d) * A]/4 to get V (volume) in cubic feet. Divide that by 27 to get cubic yards if asked. a = sum of depths of all corners common to 1 square; b = sum of depths of all corners common to two squares; c = sum of depths of all corners common to 3 squares; d = sum of depths of all corners common to 4 squares; A = area of ONE square only (NOT the entire group of squares)
Cut and Fill (Contour Method)
General purpose method that applies to a variety of situations. You can do both cut and fill in this method and would usually color fill in Blue and cut in Red. In plan, you calculate all of the area(s) of the cut or area(s) of fill. Then you add all the cuts together and separately add the fills together. Take these (individually) times the distance between contours and divide that by 27 to get cubic yards. You will then have a cu.yd. value for amount of fill and a separate value for amount of cut.
Concrete
Concrete is an outstanding material for use in the landscape and one of its primary benefits is that it is highly workable (adaptable), low maintenance costs, high durability, hard surface, and able to be used and applied to a wide variety of purposes (ex. Foundations, walls, walkways, site furnishings, etc). That said, concrete has several shortcomings, including susceptibility to cracking, low tensile strength, difficulty to color evenly and permanently, the need to install joints, prolonged curing time (~28 days) and the need for rebar and formwork. 1 cubic foot weights 150 lbs.
Concrete - Ingredients
The three principal ingredients in a concrete mix are water, cement and aggregate. Note that sand is sometimes added to concrete mixes, but is considered a less acceptable answer than aggregate, as aggregate is a broader and more inclusive term. Depending on the mix, aggregates added to concrete could take the form of sand, crushed stone or gravel, with the latter two ingredients being more common than sand. Although rebar is a necessary component to many forms of concrete construction, it is not always needed and would not constitute part of the actual concrete mix.
Concrete - Aggregate used in mix
As a general rule, aggregate used in a concrete mix should not exceed 1/3 the depth of the slab to be poured. Using the largest aggregate size possible can reduce shrinkage and cracking in concrete, however, oversized aggregate will create the opposite condition and exacerbate cracking in the concrete.
Concrete - Slump Test
The primary purpose of a slump test is to measure the workability of a concrete mix. The test itself measures the consistency of fresh concrete before it sets by placing a portion of the concrete mix into a slump cone, tamping the mix and removing the cone. The height of the mix is then measured, as is any slump or deformation in the shape of the concrete. Thus, the slump test not only checks the workability of freshly made concrete, but can also be used as an indicator of an improperly mixed batch of concrete.
Concrete - Compressive Strength
The compressive strength of concrete is determined primarily by the ratio of water to cement. Logically, this ratio is often referred to as the W/C ratio. Aggregate and rebar provide additional strength and reinforcement to concrete, but the ratio of water to cement is the primary determinant of the compressive strength of concrete.
Concrete - “Heat of Hydration”
A chemical process known as “Heat of Hydration”, or simply hydration, is initiated when cement is mixed with water to form concrete. Heat of hydration is an exothermic (heat-producing) reaction that occurs as cement particles expand due to the presence of water. The ratio of cement to water determines the extent of this reaction and is the primary determinant of the ultimate strength of the cured concrete.
Concrete - Wire Mesh
The primary purpose of welded wire mesh in a concrete slab is to reduce cracking.
Concrete - Control Joints
Control joints are installed to direct expected cracking (or reduce random cracking). They should be placed at regular intervals and keep the ‘panel’ relatively square. They should never be farther apart than 1.5x the width, so a 5’ wide sidewalk would want them spaced less than 7.5’ o.c. A control joint must also be placed where a sidewalk butts into a larger concrete area (usually separated by an expansion joint) at the corners (perpendicular to the expansion joint) of where the sidewalk hits the larger slab. So say a 5’ sidewalk was coming into a 20’ slab, there would need to be a control joint starting at either corner of that intersection and go the length of the slab (remember it runs perpendicular to the EJ).
Concrete - Expansion Joint
Isolation or expansion joints are used in concrete to allow lateral movement between adjacent slabs or other fixed structures/surfaces, and as such, should be constructed to the full depth of the concrete slab. Note that expansion joints should also be placed at the interface between concrete and other fixed surfaces, for example, where a horizontal concrete surface meets a structure. They also help create a smooth and safe walking surface.
Concrete - Doweled Joints
Doweled joints are used in slabs to reduce displacement.
Concrete - Metal Dowel
Metal dowels are typically added to concrete construction joints to transfer loads between individual slabs. Note that Tie Bars and Keyways can also be used to load transfer.
Concrete Vs. Masonry Products
Concrete has many benefits and can be used in a wide variety of landscape applications. However, there are numerous situations in which masonry products such as stone and brick prove to be more appropriate. As a general rule, masonry products have greater aesthetic variability than concrete, as well as a higher compressive strength and greater durability. Masonry products also generally exhibit better moisture resistance than concrete. That said, concrete is regarded as a less expensive and lower weight material than masonry and can be used to create a nearly endless variety of forms and structures.
“Compost Blanket”
Compost blankets are a 1-3” layer of compost loosely applied to disturbed soils. They prevent erosion and concentrated stormwater flows, reduce runoff, increase infiltration, promote the growth of vegetation and enhance soil stability in general. They therefore help protect against conditions that will create concentrated flows and high-velocity run-off. However, once concentrated flows or high-velocity run-off have been created by upstream conditions, compost blankets should not be used. So they are to Mitigate high-velocity run-off before it becomes high-velocity run-off.
Construction Details
To be as effective and clear as possible, each construction detail should contain dimensions, a scale to which the detail is drawn, orthographic linework and callouts for materials and other relevant annotations. Note that in specific circumstances, certain details may benefit from having isometric drawings that support or otherwise elucidate information contained in the orthographic drawing.
Compressive Force
Occurs when a physical force presses inward on an object, causing it to become compacted.
Detention Systems (Detention Basin)
Detention (or dry) basins, are used to control peak discharge rates, and flow is metered out of the basin until no water remains.
Detention Systems (Retention Basin)
Retention (or wet) pond that contains a permanent pool of water. This can be used for storm water management, pollutant removal, habitat improvement, and aesthetic enhancement.
Detention Systems (Rooftop Detention or Blue Roof)
Rooftop areas on low-slope roof surfaces can be utilized for detention of storm water. Usually water is ponded to a depth of no greater than 4” to keep weight down for structural load of the roof. Requires redundant drains (in case one gets clogged) and scuppers for overflow.
Detention Systems (Water Quality Basin)
Often included in the design of retention and detention basins, it provides an area for the settling out of sediments. A sediment basin is an example of this which slows the velocity of runoff in order to allow sediment particles to settle out. These need to be cleaned to remove this sediment once and a while.
Dust Control on a Construction Site
Proper dust control on a construction site will reduce the volume of sediments produced by construction activities. Although most sediment control efforts on a construction site address the presence of sediments in stormwater, dust also produces measurable amounts of sediments and should be mitigated by proper dust control. This would consist of adding a Stabilized Construction Entrance (a mountable gravel berm that helps remove mud and dirt from vehicle tires), or if not sufficient you can add a “Wash Rack” to wash sediment off a vehicle tires. Note that dust could potentially reduce soil fertility (through the loss of top soil) but this would be a minor factor compared to the types of things the LARE cares about (i.e. BMPs).
Fasteners - Snap Ties
Snap ties are a type of fastener used to hold formwork together while concrete is being poured and are designed to break away after the formwork is removed. Snap ties can remain inside concrete to provide additional reinforcement.
Fasteners - Non-stainless steel fixtures (Galvanizing)
Non-stainless steel fixtures used in exterior applications are often coated in zinc to prevent and reduce the formation of rust. Zinc coating is added to fasteners by dipping the fasteners in a vessel of molten zinc (a process referred to as hot-dip galvanizing).
Fasteners - Machine Bolt Assembly
A machine bolt assembly is typically used for metal-to-metal connections
Fasteners - Anchor Bolts
Anchor bolts are used to connect structural and non-structural elements to the concrete. The connection is made by an assembling of different components such as: anchor bolts (also named fasteners), steel plates , stiffeners. E.g. attaching a bench to an existing concrete sidewalk.
Fasteners - Lag Bolt with Expansion Shield
Lag Bolts are essentially large wood screws and an expansion shield is the plastic or metal device that gets inserted into concrete and brick to anchor the bolt in place.
Fall Zone for Playgrounds
The “fall zone” surrounding playground equipment should generally extend 6’ or more on all sides of the equipment in question. It should be noted that this metric applies to school-age children and that play equipment for infants and toddlers is permitted to have a smaller fall zone (3’).
Fertilizer (NPK values)
The ratio of Nitrogen (N), Phosphorous (P), and Potassium (K) present in fertilizer can be used to establish soil fertility. Numbers in a fertilizer (like 10-20-5 or 6-12-4) show a % of each NPK in the mix. So a 10-20-5 is 10% Nitrogen, 20% Phosphorous, and 5% Potassium blend. So if you want to apply 100 pounds of phosphorus you divide 100 by 20% (or 0.2) which means you need to apply 500 pounds of that fertilizer to reach that level of phosphorus. On the flip side, if you have a 100 pound bag of that same 10-20-5 and what to know how much Potassium you will be adding by applying it all, you would multiply the 100 pound size by the % or 100 * 0.05 = 5 pounds of Potassium. The equation would be Applied Lbs = Bag Lbs * %
Frost Line
the maximum depth of ground below which the soil does not freeze in winter.
Green Roofs
3 main types: Extensive - comprised of 2”-6” of lightweight mineral growing medium planted with drought-tolerant species, and subsisting solely on rainwater. Intensive - has deeper, more organic-rich soil and is planted with a range of plants and even trees. Weight is a big consideration with an intensive design. Modular - This system has trays that act like potted plants over layers of waterproofing, root barrier, insulation, etc. to form the complete roof coverage.