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Engineer Site Plan - Lesson 2

In a previous post , you identified all your perimeter constraints and your internal constraints (building separations, building setback, street widths, etc.). The framework of your site plan is done, now you just need to fill in some of the details. You should have your building locations identified as well as curb and centerlines of your streets.
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Definitions, Abbreviations, and Acronyms

Here we will list some common definitions, abbreviations, and acronyms applicable to all topics. Use the search feature of your browser (Ctrl+F) to find your term quicker.

Terms beginning with A
  • Aggregate Base (AB) – The coarse gravel bed for concrete and asphalt pavement. Also used as a bedding for utility pipes. Promotes drainage as well as a level surface to place the pavement.
  • Americans with Disabilities Act (ADA) – A Federal law governing the design of public and private improvements to comply with minimum usability standards which include those with many disabilities (covers all types of disabilities not just wheelchair-bound persons).
  •  – Area drain system is the inlets and pipes which collect runoff around buildings from landscaped areas.
  • As-builts – A term which refers to record drawings when a project is complete. Usually any changes that occurred during construction are updated on the plan. The As-built plan is then sent to the City for storage and future use by new developments.
  • Asphalt Concrete (AC) – The tar and aggregate material used on many streets and driveways. Its benefit is it is easy to install and easy to repair. Drawbacks include it doesn’t last as long and must be annually maintained to prevent cracking and spalling.
Terms beginning with B
  • Backflow Preventers (DCDA, RPPA) – A backflow preventer stops water from traversing backwards in a water line. Typically, this is done with two check valves.
  • Backwater Valve (BWV) – A check valve designed to prevent effluent from flowing backwards in a sewer lateral thereby preventing a spill inside the residential unit. The flow backward in the lateral can be caused by an increase in the Energy Grade Line of a sewer main built up behind a sewer main blockage, or by the build up of effluent behind a sewer lateral blockage.
    • Best Management Practices – A generic term used widely in many fields, but specifically for Civil Engineering usually refers to techniques to manage storm water run-off and erosion control.
    • Bulking Factor – A percentage increase in volume of soil from natural condition to excavated condition. A stockpile of dirt is typically not compacted, so will assume a larger volume. Bulking is only applicable to export and is used to calculate truck-loads required to haul the dirt away.
    • Building Pad (Pad) – The flat level ground where a building foundation is laid. Typically, 4” to 12” below Finished Floor.
    • Building Setback – A building setback is the minimum distance which a building or other structure must be set back from a property line, street or road, a river or other stream, a shore or flood plain, or any other place which is deemed to need protection.
    Terms beginning with C
    • California Building Code (CBC) – In the state of California, the governing document that defines how buildings are constructed is the California Building Code (CBC). This supersedes the International Building Code (IBC). Local jurisdictions may have modifications to the CBC, such as the City of Los Angeles Building Code (LABC). The latest edition is the governing version prior to approval. Once approved, that edition remains your governing version for the life of the project.
    • Catch Basin (CB) – A structure to collect runoff from streets. This includes Curb-Inlet catch basins as well as Drop-Inlet catch basins.
    • Clean-out (CO) – A small access port to the underground pipe. Typically, for smaller diameter pipes and laterals. Used for maintenance in case of a clog.
    • Conceptual Grading – Also known as preliminary grading. As the name implies, you are generating a concept that you will later refine during Precise Grading.
    • Construction Allowances – A reduction of a maximum or increase of a minimum requirement to allow for small variances in construction. Numbers included in this Guide where Construction Allowances should be applied will also include the typical reduced value inside [square brackets]. Example, 8.33% is max ramp slope per ADA, you should design as [7.75%] so any variances in construction of the ramp will not exceed 8.33% (if installed incorrectly).
    • Construction Joint – A physical break in concrete sidewalks or curbs, sometimes with a fibrous material inserted between the panels to facilitate the clean removal of the existing concrete in the event it needs to be replaced, to allow for expansion due to weather, and allow for creep due to seismic activity or storm water penetration.
    • Cross-lot Drainage – A condition where runoff from an area will travel across a lot-line to another lot not owned by the same entity. In some conditions, you will be required to accept the cross-lot drainage from an existing lot onto your project.
    • Cross-Slope – The slope of a surface perpendicular to the travel direction. Perpendicular to the Longitudinal Slope.
    • Crosswalk – A pathway across a travel way, sometimes is striped with white lines. If the path is not perpendicular across the travel way, a painted crosswalk is required (to show the pedestrian where to travel). Minimum width is 4-feet.
    • Crown – The high point in a street section, typically at the center line of the street, though it can be offset to one side or the other, or even have two crowns (in the case of a divided highway/street). Similar but not the same as a Grade Break.
    • Cubic Feet Per Second (CFS) – A common measure of volumetric flow rate.
      • Cul-de-sac (court) – A Cul-de-sac is a circular turn around at the end of a dead-end street with or without a center island. The radius of the cul-de-sac is based on the required local fire truck turning radius or city minimum standard. Also known as a court.
      • Curb Ramp – A sloped hard surface that is intended to surmount a curb that is adjacent to a roadway. No handrails are required (like a normal ramp requires).
      • Curb Return – A curb return is the curved portion of a curb which connects intersecting streets. Often one or two Curb Ramps are constructed in this section.
      Terms beginning with D
      • D-Load (RCP only) – The supporting strength of a pipe loaded under three-edge-bearing test conditions (supported on 3 sides) (N.B. pipes do not have “sides” but follow the theory anyway) expressed in pounds per linear foot of inside diameter or horizontal span. The numbers range from D-800 to D-3850 based on the diameter as well as the anticipated depth below surface and the bearing capacity of the soil. Some local jurisdictions have referent tables or use the next overseeing jurisdiction. When none can be found, default to LA County Public Works Design of Reinforced Concrete Pipe.
      • Deepened Footing (DF) – A building foundation footing that extends deeper than the standard design as set forth by the Structural Engineer’s plans. A detail is required on our plans or on the Structural Engineer’s plans which describes how the deepened footing is to be constructed. On the plans, you identify the amount to add to the typical footing depth, as well as the start and stop locations. Deepened footings should be in 2” increments. Deepened footing depths can vary along the face of a building.
      • Division of Drinking Water (DDW) - The governing body setting standards to ensure safe drinking water. The DDW is part of the State Water Resources Control Board (SWRCB).
      • Drainage Fixture Unit (DFU) – A shorthand method of the anticipated discharge from a fixture. Not a true estimate of the maximum flow, or the max possible volume of flow from that fixture. Plumbers use these estimates to size the water and sewer pipes within a building and we use them to size sewer pipes outside of the building.
      Terms beginning with E
      • Easement – A legal granting of rights to a portion of a property to another entity for maintenance or access purposes. Easements are usually granted to a Public agency to allow said agency to maintain a public utility such as a sewer system. Easements can also be granted to private parties for such things as a shared access driveway.
      Terms beginning with F
      • Feet Per Second (FPS) – A common measure of velocity flow rate.
      • Finished Floor (FF) – The elevation of the finished interior floor of a unit or building. Usually the top of the Structural Slab.
      • Finished Ground (FG) – The elevation of a dirt surface in its final condition. This elevation is shown with only 1/10th foot precision (0.1).
      • Finished Surface (FS) – The elevation of a hard surface such as concrete sidewalk. This elevation is shown with 1/100th foot precision (0.01).
      • Fire Department Connections (FDC) – An FDC is used to add water to a building sprinkler system. It is used most often when the main system has lost pressure (due to any number of factors, most common is wide-spread localized structure fires). The Fire Department closes the Post Indicator Valve (PIV) and then connects a Pumper Truck to the FDC and pumps water into the building sprinkler system.
      • Fire Hydrants (FH) – A fire hydrant is a connection point by which firefighters can tap into a water supply.
      • Flowline (FL) – The lowest point in the cross-section of a dirt swale or concrete gutter.
      Terms beginning with G
      • Gallons Per Minute (GPM) – A common measure of volumetric flow rate.
        • General Plan – A general plan is a broad planning guideline to a city's or county's future development goals and provides policy statements to achieve those development goals.
        • Grade Break (GB) – A change in slope of a surface or pipe.
        • Grind and Overlay – A technique of rehabilitating existing asphalt in an area where a section of the asphalt is removed due to construction and then must be replaced and joined to existing asphalt. Asphalt cannot have an abrupt join and must be “blended” by removing a top layer of existing and replacing with new.
        Terms beginning with H
        Terms beginning with I
        • Invert (INV) – The lowest inside point in the cross section of a pipe.
        Terms beginning with J
        • Junction Structure (JS) – A structure typically without a shaft and manhole lid. Usually for pipe size changes or combination of flows where access is provided elsewhere close by. See also Manhole.
        Terms beginning with K
        • Knuckle – A type of curved street where the outside curb is pushed outward to create a larger travel way or parking area around the outside of the curve. The offset can be anywhere from 5-feet to 20 or more feet.
        Terms beginning with L
        • Level Landing – A flat plane of concrete that does not exceed 2% in any direction (Maximum Slope). The lateral dimensions of a landing vary based on the conditions, though typically 4-5 feet on each side. Care must be taken to properly calculate the maximum slope of the landing. Example: If a slab has a 2% slope in one direction (longitudinal slope), and a 2% slope in the perpendicular direction (cross-slope), the max slope of that slab is 2.82%. Examples of perpendicular slopes that do not exceed 2% max:
          • 1.40% and 1.40% = 1.97%
          • 1.70% and 1.00% = 1.97%
        • Longitudinal Slope – The slope along the travel way or length of a surface. Measured perpendicular to the Cross-slope.
        • Lot Line - A boundary between legal parcels within the same tract.
        Terms beginning with M
        Terms beginning with N
        Terms beginning with O
        • Operational Safety Hazard Administration (OSHA) – The governing body setting minimum workplace standards to ensure safety of workers and the general public.
        • Over-excavation (Over-Ex) - Over-excavation is the additional removal, replacement, and compaction of native dirt usually under building foundations. Refer to the Geotechnical Report for exact value to use for your project.
        Terms beginning with P
        • – A parcel is a division of land that contains fewer than 5 smaller lots. A parcel map is a legal document identifying the limits of the lots as well as any existing or proposed easements.
        • Pipe Joint Types:
          • Flanged (FL) – A flanged end of a fitting or pipe has a ring which has bolt holes spaced evenly around and is mated with another flanged end and secured with bolts.
          • Push-On (PO) – A push-on end uses friction from a gasket to maintain the connection between a fitting and a pipe or between two pipe segments. Typical for PVC pipe.
          • Mechanical Joint (MJ) – A mechanical joint has a flange on the fitting side of the connection and a plain end on the pipe side, a wedge is then bolted to the flanged end and driven in between the flanged end and the side of the pipe, thereby creating a more secure connection on a smooth, un-flanged pipe.
        • Pipe Materials:
          • Ductile Iron Pipe (DI) – Metal pipe, which is preferred by public agencies.
          • High Density Polyethylene Pipe (HDPE) – A plastic pipe that is rigid and durable. HDPE fittings can be used to design bends in the alignment without a structure.
          • Polyvinyl Chloride Pipe (PVC) – Plastic pipe, which is preferred by developers due to lower cost, ease of installation, resistance to corrosion, and its durability.
          • Reinforced Concrete Pipe (RCP) – A pre-cast concrete pipe that can be formed into sizes from 18” to 120” in diameter. Pipe can be designed with curves. Changes in direction require a structure. Used less often for smaller pipe, HDPE is favored. In public R/W it’s favored over plastic alternatives.
          • Stainless Steel (SS) – Not used very often for water systems.
          • Vitrified Clay Pipe (VCP) – A clay pipe that has been coated to prevent scour. Used less often, PVC is favored though some public agencies still require VCP.
        • Podium Buildings – Podiums are typical for apartment style developments where the first level (or many subterranean levels) are designed for parking and the living spaces are many levels above.
        • Portland Cement Concrete (PCC) – A type of concrete commonly used for sidewalks, streets and curbs.
        • Pothole – A technique where a hole is dug at specific locations to find and investigate existing utilities either for connection or avoidance purposes.
        • Precise Grading – Also known as fine grading or final grading. The design as it shall be after construction is complete. It is a refinement of the conceptual grading.
        • Pressure Reducing Valves (PRV) – A manufactured device designed to reduce the pressure of a water system. The valve can be manufactured to reduce the pressure to a set pressure level or reduce it by a fixed amount.
        • Post Indicator Valves (PIV) – A PIV is a gate valve with a vertical post that has a window with a sign that indicates if the valve is currently open or closed. The sign changes from closed to open by means of turning a nut on top of the PIV, which also opens or closes the valve. It is meant to make it certain the valve is open during emergency situations.
        Terms beginning with Q
        • Q (flow) – A term used to describe the volumetric flow expected as surface run-off from a particular are during a storm, or the amount of volumetric flow expected in a storm drain pipe.
        Terms beginning with R
        • Ramp – A pedestrian ramp is any hard surface that exceeds 5% longitudinal slope and is intended for pedestrians of any kind. See also Curb Ramp.
        • Restrained Joints or Joint Restraints (RJ) – Restrained Joints are mechanical devices added to push-on connections to add more strength to the joint.
        • Right-of-way (R/W or ROW) – A right-of-way is a right to make a way over a piece of land, usually to and from another piece of land. A right of way is a type of easement granted or reserved over the land for transportation purposes, such as a highway, public footpath, rail transport, canal, as well as electrical transmission lines, oil and gas pipelines.
        • Rough Grading – Also known as mass grading or interim grading. Often it will take a good amount of work to get a site from it's existing condition to one that is relatively close to the final state. The rough grading is the middle step after removal of structures and debris from the site, allowing grading operations to begin without the Precise Grading being completed.
        • Run-on/ Run-off – A term to describe storm water crossing into another area or another property. If the water enters your property, it's called Run-on. If your water leaves your property it's called Run-off. Run-off is also a generic term for storm water discharge that is generally surface flow.
        Terms beginning with S
        • Secondary Outflow/ Overflow – A path for runoff to take that protects living spaces including garages. This designed path conveys the water to the perimeter of the project in the event of a drainage system malfunction. Care must be taken to provide a Secondary Outflow in sump locations. A Secondary Outflow may be over the ground, or a separated drainage system.
        • Sill – The sill is a small raised portion around the perimeter of a building where the toe plate is nailed for wall framing, just above or at the same elevation as the FF. The Sill is most noticed in the garage where the garage floor slopes towards the door, but the sill remains at the level of the FF.
        • Shrinkage – Shrinkage is the consolidation of native soil when placed and compacted compared to the natural volume before disturbance. Example: A shrinkage factor of 20% means the soil will compact and occupy 20% less volume than the native condition, requiring an additional 20% of soil to fill the same hole.
        • Slope – Two definitions:
          • The rate of elevation change of a surface over a given distance. Typically, the slope of a surface is given in percent, which is the vertical distance divided by the horizontal distance. Example: 2%.
          • The evenly graded surface between two finished grades of vastly different elevations. Typically, a graded slope has a rate of change given as a ratio of the horizontal to the vertical. Example: (H:V) 2:1.
        • Soffit – The highest inside point in the cross section of a pipe. When changing pipe diameters, usually the soffit elevation is matched on each pipe so that the flowline of the smaller diameter pipe is higher than the flowline of the larger diameter pipe.
          • Specific Plan – Similar to a General Plan, a specific plan is for a clearly outlined area of a municipality or for a certain parcel of land. The Specific Plan can supplement the General Plan by allowing some outlined variances.
          • Spring Line – The midpoint in the cross section of a pipe.
          • Standpipe – 
          • Standard Plan – Standard plans are details for various construction items representing the current policies of the local jurisdiction. Many cities and agencies have their own standard plans. Additionally there are county, state, and national standards which could be used on your project.
          • Standard Plan for Public Works Construction (SPPWC) – A national standard published by the American Public Works Association. These standard plans are often acceptable to local jurisdictions, especially when there are no other standard plans available for that item.
          • Structural Slab – The thickness of both the slab and the bedding of the foundation of a building. The thickness can vary based on the type of construction and the soil conditions. The Slab sits on the Pad. The Finished Floor elevation is the Pad plus the Slab thickness and any sand or base. Consult with the project Structural Engineer for slab design.
          • Storm Water Pollution Prevention Plan (SWPPP) – A SWPPP is a water quality report for the construction phase of the project.
          • Sump Condition – A condition where runoff collects at a low point in the site. Typically, a Catch Basin or Area Drain is placed at this location. A Sump Condition should have a well-defined Secondary Outflow path in the event the drainage system malfunctions.
          Terms beginning with T
          • Tract or Tract Map – A tract is a division of land into smaller lot(s). The lots may be sold a separate deeds, or remain as a larger property bound by common rules.
          • Traffic Index (TI) – A measure of the frequency and type of traffic that is projected for a certain area. The TI is used to determine the proposed street structural section.
          • Truncated Domes – A detectable surface designed to aid Handicapped persons while crossing vehicle travel-ways. Typically, the bottom 3-feet of a Curb Ramp has truncated domes. Also, may be required at Zero Inch Curb locations.
          • Turning Radius – 
          Terms beginning with U
          Terms beginning with V
          • Vertical Curve (VC) – A vertical curve is a parabolic curve that connects two tangents of different slopes by means of a constantly changing transition. Vertical curves are generally 50-feet in length or more, but on private streets, shorter vertical curves can be used.
          Terms beginning with W
          • Water Quality Devices – Proprietary systems that treat runoff for specific pollutants including sediment. Some have integrated catch basins, filter media, trees, and irrigation.
            • Water Quality Management Plan (WQMP) – A WQMP/ WQTR/ (various other names) report is for the duration of the project after construction is complete and includes long term Water Quality devices.
            • Wye (sewer) – A standard wye is a Y-shaped fitting which allows one pipe to be joined to another at a 45° angle.
            Terms beginning with X
            Terms beginning with Y
            Terms beginning with Z
            • Zero Inch Curb (0”CF) – A curb that does not have a face. It is flush with the adjacent pavement. Typically used at driveways and Curb Ramps.
            • Zoning and Land Use – Zoning is the process of dividing land in a municipality into zones (e.g. residential, industrial) in which certain land uses are permitted or prohibited.

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