Indiana LICA Contractor Certification Training Workshop

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Indiana LICA Contractor Certification Training
Workshop

• 2008
• Basic Surveying Concepts

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Basic Surveying Concepts

• What you need to know to perform correct
  construction and checkout of NRCS practices
• Ability to work with benchmarks that do not have
  elevations of 100.00
• Ability to work with both rod readings and
  elevations
• Ability to use the slope equation
• Ability to establish your own benchmarks and turn
  points
• Ability to perform a bench level circuit

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Basic Surveying Concepts

• Benchmarks with elevations not 100.00
• NRCS is using GPS survey grade equipment to
  survey more and more practices as we progress
• Survey Grade GPS will not be using an elevation
  of 100.00 for benchmarks most of the time
• The concept is the same regardless of the
  elevation of the benchmark

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Basic Surveying Concepts

• Waterway Scenario

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Basic Surveying Concepts

• With surveys based on benchmarks with Elevation
  of 100.00
• 1. You set up your laser (on zero grade!) and
  take a shot (Back Sight- BS) on the benchmark
• 2. You add that rod reading to 100.00 to get the
  height of the instrument (HI)
• 3. Then to obtain elevations you subtract your
  next rod readings (Fore Sights FS) from the HI

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Basic Surveying Concepts

• When you use a benchmark of a different
  elevation, its the same process

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Basic Surveying Concepts

• Obtaining elevations from HI (HI FS
  Elevation)

• Ground shots and their elevations are rounded to
  tenths (0.X) of a foot

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Basic Surveying Concepts

• Normally when you set up you can not see the
  entire project from that one set-up
• In these cases, you have to perform what is
  called a turn

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Basic Surveying Concepts

• Performing a turn requires
• A solid Turn Point that will not move while
  surveying
• A Fore Sight on the Turn Point to determine its
  elevation from HI
• Move the instrument to a new location
• Take a Back Sight on the Turning Point to
  determine the new HI
• Continue surveying/ checkout

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Taking a FS Shot on the Turn Point (TP)

• Shots on hard objects can be recorded as
  hundredths (0.XX) of a foot
• All Benchmark shots and turn points should be
  this way

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Basic Surveying Concepts
3.97
3.86
3.75
3.82
Odd hundredths are at the bottom of the black
marks (0.01, 0.03, 0.05, 0.07, 0.09)
Even hundredths are at the top of the black marks
(0.02, 0.04, 0.06, 0.08)
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Basic Surveying Concepts
-Taking a Back Sight (BS) on the Turn Point
(TP) -Since we know the TP elevation from the
previous Fore Sight (FS), we take a BS on the TP
to obtain the new HI
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Basic Surveying Concepts
With a new HI established, you can continue
taking checkout shots which are all Fore Sights
(FS)
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Basic Surveying Concepts
If you can shoot the original TBM from your
second set-up do so and make sure your TBM
elevation checks out as the same elevation from
when you started.
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Basic Surveying Concepts

• If you cant see the original benchmark or the
  instrument is too high for you to shoot it,
  youll have to make another turn back to complete
  your checkout notes.
• This has to be done to verify the math of all
  your shots.
• This is also how you can check to see if our
  TBMs are correct in case you are having trouble
  with them.

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Basic Surveying Concepts

• When you begin with a benchmark and checkout your
  project and complete one or more turns and then
  turn back into the benchmark to check yourself,
  you have completed a bench level circuit.
• Your project checkout shots (waterway grade,
  bottom width, etc.) really arent part of the
  circuit as they dont verify the shots taken on
  the benchmarks and turn points.

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Basic Surveying Concepts

• The Slope Equation
• Slope Change in Elevation/ Change in Distance
• Example
• The elevation at station 1100 is 564.3 and the
  elevation at 1250 is 565.5
• The change in elevation is (565.5 564.3 1.2)
• The change in distance is (1250 1100 150)
• Slope 1.2/150 0.008 which is 0.8
• This means that for every 100 the constructed
  grade goes up or down 0.8