PURPOSE: To reduce the amount of pumping by a method wherein strainers are provided to an outer pipe on locations where water stays, an inner pipe, smaller in diameter than the outer pipe, is provided, water collecting chambers are provided to locations where the strainers are provided and drain pumps for drainage in the water collecting chambers are provided.
CONSTITUTION: A casing 2 is inserted up to a specified depth while a hole 1 is excavated, and an outer pipe 4 is buried with strainers 3a and 3b provided to water-staying layers W and W'. Then, the casing 2 and space around the locations where the strainers 3a and 3b are provided in the outer pipe 4 are filled with permeable material 5 while the outer pipe 4 in an impermeable layer Y is filled with water-expansion clay 6, and thereby water-running between the water-staying layers W and W' is stopped, and then the casing 2 is extracted. Then, the outer pipe 4 is blocked with a bottom plate 7 on a location near the strainers 3a, and water collecting chambers 10a and 10b are provided with the water pipe 4 and the bottom of an inner pipe 8 blocked with partition plates 9. As occasion demands, drain pumps 11 are installed to the water collecting chambers 10a and 10b, and drainage is made therewith. Thereby, the amount of pumping can be reduced by executing drainage as occasion arises in accordance with the degree of springwater.
OKAMURA TAMENOBU
NAKANISHI HIDEKAZU
FURUTA TAKAHARU
