the mammoth vibro - tamper ( mvt ) is a ground improvement technique whereby loose soils can be effectively and economically densified and improved to permit development . the technique consists of the repeated impacting of the soils using a heavy weight which is vibrated using an electrically driven vibrator . treatment is performed in a pre - planned grid pattern , the degree of improvement being dependent on the size of the weight , the frequency and amplitude of the vibrations , and the dwell time for each application of the tamper . the equipment consists of a heavy steel plate attached to a purpose - built , low frequency , high amplitude vibrator . the unit is suspended from a crane through a purpose - build shock absorber fitted to the main line . a control panel and generator are mounted on the back of the crane . the vibro - tamper technical principle was developed and applied by fudo construction co ., ltd . ( predecessor of fudo tetra corporation ). in addition , the improved grounds by vibro - tamper have a reputation of enduring huge earthquakes in japan . fig1 is a map like illustration depicting the locations of huge earthquakes where liquefaction mitigation effect by vibro - tamper was verified . of particular interest , the vibro - tamper technology has been applied for compaction of reclaimed land at kansai international airport and satisfied results have been obtained as shown . during the huge seismic motion of the hyogoken nambu earthquake in 1995 , there was no serious damage to the airport runway . unique to mvt is the ability to use smaller cranes for movement of the tamping device , versus a free fall weight , and the reduction in vibration and noise associated with a free fall weight . unique to compaction is the soil found in florida and parts of new zealand which consists of sand and limestone . of great concern is the limestone pinnacles that form and need to be dispersed for proper foundation . for instance , ft . lauderdale airport located in southeast florida , u . s . a . in undergoing an expansion that revealed the issues of soil compaction for use with limestone pinnacles . in particular , ft . lauderdale is expanding the south runway from 100 feet to 150 feet and extending the length from 5 , 200 feet to 8000 feet . the steps necessary to effectively compact the soil for use in the runaway expansion begin with establishing a grid pattern for a worksite . the grid pattern developed for this invention consists of individual partitions of about 150 ′× 120 ′. this permits a sized partition that reduces or eliminate the need for crane repositioning while the partition is being serviced . before tamping begins , an spt test of the individual partition is performed . this spt test will be compared to a second spt test when the tamping sessions are complete . a first tamping session is formed consisting of placing a first tamper plate sized about 10 ′× 10 ′ on an individual partition and initiate tamping in position for about 90 seconds . the first tamping session is repeated by overlapping each tamped position until the entire partition has been tamped . upon completion of the first tamping session , the partition is allowed to settle for about 96 hours ( 4 days ). it has been found that water and soil upheaval is expected during the first session wherein the pore water pressures that rises up from the first session is then allowed time to eliminate completely . the spt ( standard penetration test ) is an in - situ dynamic penetration tests to provide information on the geotechnical engineering properties of the soil . the test is conventional and employs a sample tube that is driven into the ground at the bottom of a borehole using a slide hammer wherein the number of impacts needed to penetrate the tube is recorded providing an indication of the density of the ground for use in an empirical geotechnical engineering formula . a second tamping session is then performed again using the first tamper plate on the first individual partition and the tamping is initiated in position for about 120 seconds . the tamping is repeated in subsequent positions wherein the tamping plate is partially overlapped on the previous tamping position until the first partition has been fully tampered a second time . the partition is then allowed to settle for about 96 hours ( 4 days ). it has been found that no visible water and no upheaval occurs after the second session . a third tamping session consisting of placing a second tamper plate having a size of about 7 ′× 7 ′ on the first individual partition and initiate tamping in position for about seconds . the third tamping session is repeated throughout the partition by overlapping each tampered position until the partition has been fully tampered . after each session is completed , but no earlier than six days after an individual partition has been completed , the soil is retested for compaction . the vibration method using two separate tampers is quite effective for the sandwich layer structure of sand and limestone in florida from test trials . referring to fig2 , set forth is a 1st tamping illustration where some amount of water tends to come up from the ground to the surface . the pore water pressure tends to become high ( dilatancy effect ) because of shear deformation during tamping . the compaction energy seems to be consumed by the compaction in upper loose sand layer only , so the limestone layer below remains loose . referring to fig3 , after the second tamping no water came to the surface and substantial settlement in the range of 0 . 5 feet to 2 feet is observed . this suggests that the upper sand layer was densified already and the loose limestone layer was well compacted after the second tamping due to sufficient compaction energy through the densified sand layer . the preferred vibro - tamping device is moved by a crawler crane having an 80 - 250 ton capacity with a three part sheave block . it is noted that the crane is used only for positioning of the tamping plate , as opposed to the conventional dynamic compaction technique wherein a 20 ton weight is lifted upwards of 100 feet from the ground and allowed to free fall . for this reason a relatively low crane can be used which is a benefit in cost , safety in high winds , and safety around airports where any high crane can be a hazard . the first tamping plate is a 10 ′× 10 ′ unit , preferably a 340 kva generator is used in operation . the second tamping plate is a 7 ′× 7 ′ unit . while the two sizes listed are preferred , the concept is directed to the use of two different sized tamping plates , the first being larger than the second by about one third size . the tamping plates preferably include a cross plate attachment on the impact side used as a temporary anchor to prevent the tamping unit from walking . the cross plate is about 24 ″ deep and about 1 ″ thick , two plates are welded to the impact side in a cross pattern to prevent waling in any direction . the second tamping plate , such as 7 ′× 7 ′ is effective to compact loose sand in between pinnacles as shown in fig4 . fig5 depicts a sandwich layer structure with an elevation at + 3 . 5 ft , limestone and multi - layer structure between + 0 . 5 ft to − 5 . 0 ft , limestone material layer at − 5 . 0 ft and white sand material layer at − 7 . 0 ft . referring to fig6 , with regard to the compaction energy , mvt has higher energy level than the energy of conventional ddc . for instance , if we assume 100 seconds mvt tamping , the energy level is estimated as follows : in spite of the high compaction energy , vibration levels at the surrounding ground and facility during mvt operation is lower than that of ddc operation . in general , mvt operation will not cause serious damage to the surrounding structures as long as the distance of more than 10 meters ( 33 feet ) is kept . in conditions of very hard lime - rock layer or rock , it can be difficult to break the layer and properly compact the sand between the layers . in such instances the use of prefacturing is desired by use a drilling or trenching . drilling can be used to break the lime - rock coverage prior to tamping , the drilling is by an auger machine with the holes arranged in a pattern to provide proper breaching of the lime - rock layer . trenching is performed by an excavator that digging a trench about every 10 feet . both the drill hole and the trench should be between 10 and 20 feet deep . one skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned , as well as those inherent therein . the embodiments , methods , procedures and techniques described herein are presently representative of the preferred embodiments , are intended to be exemplary and are not intended as limitations on the scope . changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims . although the invention has been described in connection with specific preferred embodiments , it should be understood that the invention as claimed should not be unduly limited to such specific embodiments . indeed , various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims .