... , 2.the blowhole, 3.the tension bar, 4.inside jotting board, 5. The manhole cover, 6.inside ladder, 7.outside ladder ... , 8.enters board, 9. The overflow outlet, 10.the water inlet, 11.the ... steel frame, 14. The drainage outlet.15. The drainage board, 16.The bottom board, 17.The outside jotting board, 18.the side board GRP water tank