Ground Surface/Volume Comparisons Between Cylindrical Barriers and the Rapid Barrier System
|Ground Surface Contact (inches)||Volume (cubic inches)||Weight of Water (pounds)|
|12 inch high cylindrical barrier @ 12.5 ft. length||4 - 5||16,971||613|
|12 inch high Rapid Barrier @ 12.5 ft. length||18||32,400||1,420|
|20 inch high cylindrical barrier @ 25 ft. length||6 - 7||94,248||3,406|
|20 inch high Rapid Barrier @ 25 ft. length||28||180,000||6,502|
|42 inch high cylindrical barrier @ 25 ft. length||16 - 18||415,800||15,021|
|42 inch high Rapid Barrier @ 25 ft. length||63||793,800||28,677|
The above figures are approximate! The figures are calculated based on non-flexible material such as steel. Because flexible barriers bow out they will contact more ground surface, accept more water and therefore will weigh more than the figures stated above.
While ground surface contact and volume/weight of water is much higher for rectangular barriers, it may not be necessary to completely fill the barriers with water. The decision to do so will depend upon the judgement of those setting up the barrier considering the anticipated height and velocity of the on-coming floodwaters; in many cases barriers can for example, be filled 2/3 their stated height or less with water, with the balance of the barrier filled with air.
Air filling can be accomplished from a variety of sources. Leaf blower, shop vac even a hair dryer (separate heat and fan switches with the heat shut off). The advantage of partial air filling is that the target barrier height can be achieved much more rapidly than by filling solely from a garden hose.
Do not exceed recommended height for the barriers regardless of whether filled by air or water!