I would use a simple vlookup() for this. If your supplied data table looks something like this...

A
B
C
1
150
0
1
2
8
70
2
3
77.5
3
4
82.5
4
5
87.5
5
6
95
6
7
100
7
8
130
8

A1= depth given
B1=VLOOKUP(A1,$B$1:$C$8,2,1) will return the volume from that table