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  1. 1. Using rise and fall method
    In this method booking is done in the following manner,
    B.S
    I.S
    F.S
    Rise
    Fall
    R.L
    Remarks
    2.570
    -
    -
    -
    -
    100.00
    A
    3.750
    -
    1.200
    1.370
    -
    101.37
    C.P
    -
    -
    3.750
    -
    0.70
    100.67
    B
    5.620
    -
    4.950
    1.370
    0.70
    -
    -
    1) On any page of book, the first reading is always a B.S and last reading is always a F.S. If you are not getting F.S as last reading on each page, then it means you have done mistake while booking readings.
    2) From the B.S next F.S is subtracted. If the answer is positive (+), it will be Rise and if the answer is negative (-) it be Fall and put that reading in respective box.
    3) In the above table, I have assumed that Reduce Level (R.L) of point A is 100.0 and you can see R.L of point B is 100.67, which shows that point B is .67 units higher than point A.
    In case of numerous readings, the check should be applied at the end of each page while booking reading,
    ∑ (B.S) - ∑ (F.S) = ∑ Rise - ∑ Fall = R.L of last point - R.L of first point; 5.620 - 4.950 = 1.37 - 0.70 = 100.67 - 100.00 = 0.67 = 0.67
    2. Using height of collimation method (H.O.C)
    For this method use the following formulas,
    R.L + B.S = H.O.C and H.O.C - F.S = R.L
    B.S
    I.S
    F.S
    H.O.C
    R.L
    Remarks
    2.50
    -
    -
    102.50
    100.00
    -
    1.75
    1
    1.95
    102.30
    100.55
    -
    -
    2.55
    -
    -
    99.75
    -
    -
    2.70
    -
    -
    99.60
    -
    2.95
    -
    3.10
    -
    99.20
    -
    -
    -
    2.75
    -
    99.40
    -
    7.20
    -
    7.80
    -
    -
    -
    All other considerations are same as Rise/ Fall method. Below check have applied,
    ∑ (B.S) - ∑ (F.S) = R.L of last point - R.L of first point = 7.2 - 7.8 = 99.4 - 100 = -0.6 = -0.6

  2. Types of sewers and sewer systems

    Environmental Engineering · Structural Community · 06/05/2025 05:18 PM

    Types of sewers
    1. Sanitary sewer
    It carries sanitary sewage i.e. wastewater from municipality including domestic and industrial wastewater.
    2. Storm sewer
    It carries storm sewage including surface runoff and street wash.
    3. Combined sewer
    It carries domestic, industrial and storm sewage.
    4. House sewer
    It is the sewer conveying sewage from plumbing system of a building to common/municipal sewer.
    5. Lateral sewer
    This sewer carries discharge from house sewers.
    6. Submain sewer
    This sewer receives discharge from two or more laterals.
    7. Main or trunk sewer
    It receives discharge from two or more submains.
    8. Outfall sewer
    It receives discharge from all collecting system and conveys it to point of final disposal.
    Types of sewer systems
    1. Separate system
    If stormwater is carried separately from domestic and industrial wastewater, the system is called separate system. Separate systems are favored when:
    There is an immediate need for collection of sanitary sewage but not for stormwater.
    When sanitary sewage needs treatment, but the stormwater does not.
    2. Combined system
    It is the system in which the sewer carries both sanitary and stormwater. Combined system is favored when:
    Combined sewage can be disposed off without treatment.
    Both sanitary and stormwater need treatment.
    Streets are narrow and two separate sewers cannot be laid.
    3. Partially combined system
    If some portion of storm or surface runoff is allowed to be carried along with sanitary sewage, the system is known as partially combined system.
    In urban areas of developing countries, mostly partially combined system is employed.
  3. History of electronic distance measurement
    In surveying distance measurements were always a challenge for surveyors specially when long distances were to be measured with high accuracy. In 1950 scientist tried to calculate the distance by using light beam to travel over unknown distance with measured time.
    Ordinary lights travels at a velocity of 186,000 miles per second, therefore the time taken will be very small to cover a short distance . This idea was soon dropped but the scientists succeeded in finding a low velocity light beam in form of Infra Red Rays generated by solid state Gallium Arsenide Diode (GAD). This was put into laboratory experimentation in 1960 and finally instrument called Electronic Distance Measurement came into existence. Initially the instruments were very expensive but as the demand increased the price was within the reach of most professionals.
    Revolution in surveying due to EDM
    Modern EDM equipment contains hard-wired algorithms for reducing the slope distance to its horizontal and vertical equivalent. For most engineering surveys, Total stations combined with electronic data loggers are now virtually standard equipment on site. Basic theodolites can be transformed into total stations by add-on, top-mounted EDM modules. The development of EDM has produced fundamental changes in surveying procedures e.g.
    Traversing on a grandiose scale, with much greater control of swing errors, is now a standard procedure.
    The inclusion of many more measured distances into triangulation, rendering classical triangulation obsolete. This results in much greater control of scale error.
    Setting-out and photogrammetric control, over large areas, by polar coordinates from a single base line.
    Deformation monitoring to sub-millimetre accuracies using high-precision EDM
    The latest developments in EDM equipment provide plug-in recording modules, capable of recording many thousand blocks of data for direct transfer to the computer. There is practically no surveying operation which does not utilize the speed, economy, accuracy and reliability of modern EDM equipment. For example the EDM instrument Model # LEICA RM100 BUILDER POWER have the following particulars,
    Absolute circle reading
    Laser plummet
    Endless drives
    30x magnification
    Dual-Axis compensation
    High resolution LCD display
    Electronic laser distance measurement
    Graphic sketches
    EDM measurement with red laser on target
    Upload and transfer data
    Data editing and exchange
    Connectivity to 3rd party devices
    Hence, the advent of EDM equipment has completely revolutionized all surveying procedures, resulting in a change of emphasis and techniques. Taping distance, with all its associated problems, has been rendered obsolete for all base-line measurement. Distance can now be measured easily, quickly and with great accuracy, regardless of terrain conditions.

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