ABSTRACT
This chapter focuses on one particular type of linear measurement: the distance around the outside edge of an area or object—the perimeter and circumference. Linear measurement is simply the measurement along a line. These lengths may be expressed using the English System of measurement, feet, yards, and miles, or using the Metric System of measurement, such as millimeters, centimeters, meters, and kilometers. Many water and wastewater calculations require tank or channel dimensions, pipe lengths and diameters, weir lengths, and other linear measurements. Although these dimensions are normally provided in the treatment system plans and specifications, it may be wise to verify the lengths indicated. The diagram to the right illustrates that as the diameter gets larger, so does the circumference. In fact the circumference is about three times the length of the diameter. A radius is the distance from the center of the circle to the outside edge. It is always one-half the length of the diameter.
