| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent earth and sand from being left in a site where they cannot be collected when the balance between the discharge amounts of a water supply pump and a sand pump is broken in a sand removing method where earth and sand deposited on the bottom surface of a settling basin is collected into a sand collecting pit by a low pressure sand collecting method and the collected earth and sand are removed by the sand pump. <P>SOLUTION: When the water surface of the sand collecting pit reaches an abnormally high water level higher than the upper surface of the sand collecting pit, at least water jetting and sand pumping are stopped. In a preferable example, when the abnormally high water level continues for a predetermined time or longer, the water jetting and sand pumping are stopped. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
