parallel to the shore and the sand ceases its journey,, 



This continuous wave action would cause the sand to fill the 

 whole western area between the western breakwater and the lighthouse 

 point and on occasions it would fill the anchorage and close it 

 completely^ This same wave action which causes the continuous 

 journey of the sand has formed bay-mouth bars in front of Juchitan, 

 isolating these lakes from the sea, there remains only a small exit, 

 maintained by the tidal currents and also by the rivers which flow 

 into the lakes. 



In Salina Cruz Bay there is not a strong tidal current but only 

 a weak one that flows into the harbor and this current has not been 

 able to maintain a channel,, The sand which arrives from the west 

 would obstruct the harbor and completely block the entrance „ 



This problem was studied by the commissioners of Free Ports 

 and after much thought it was decided to build a firm s tructure 

 near the end of the western breakwater on the side where sand ac- 

 cumulates and to install powerful suction pumps to take up the 

 sand and pump it around the harbor along the wharves, to the other 

 side of the eastern breakwater where it would be deposited on the 

 shore o The sea will continue to force the sand toward the east 

 as it has done up to now„ 



Careful studies were made and capable contractors of the United 

 States were consulted and finally enough money was obtained from the 

 Mexican Government to complete the structure „ It consists of three 

 large sections each one being twenty meters long and twelve meters 

 wide o These sections were placed on a line parallel with the break- 

 water near the end of a protective rubble mound » The sections with 

 walls one and a half meters thick and transversal partitions of the 

 same thickness were lowered into position,, using their own weight 

 to force the sand out of the interior „ This procedure was called 

 "Chinese Pit" and we believe that this is the first time an operation 

 of this nature has been attempted on such a large scale in either 

 Mexico or America,, This operation was accomplished, and though 

 laborious, the sections were lowered in perfect alinemento The base 

 of these sections rest 15 meters below low tide» 



On these sections,, a room 60 meters long was built to house 

 the dredge equipment which included the pumps and their motors, 

 generators s electric motors, and pumps for refrigeration, vaccum, 

 etc, but care had to be taken to get duplicate machinery in order 

 to maintain a reliable operation at all times,, The pumps pick up 

 the sand from the seaward side through six suction tubes which are 

 moved by special apparatus, up, down and to the sides like a fan„ 

 The movement of the six tubes cover the entire area along the front 

 of the structure making a large pit 10 meters deep,, Sand arriving 

 from the west continually falls into this pit„ w This is a real sand 

 trapo" The suction tubes are moved by cranes operated from a booth 



