chambers bottom plates

[sunrise111]

1. chambers bottom plates - ?
2. Trays - ?

Sequence of pipe installation work shall be as follows:

Manhole and chambers bottom plates are fixed prior to pipes lowering;
Manhole and walls are erected after pipe laying, installation of fixing and stop valves;
Trays in sewer manholes are fixed after pipe laying and erection of manhole walls to pipe crown;

[bondar-s]

1. Пластины (плиты, панели) уложенные на нижнем основании
(на полу) камеры.
2. Поддон, желоб (Не очень понятно, но наверно у Вас есть рисунки?