Multiple drop downs

Hi Gang
I'm playing with a spread sheet that will help me calculate total waste pounds based on unit costs.
I'm having issues trying to make drop down boxes from previous selections to define the waste item. Example if I choose a type in Column B, I would like to get it to add a drop down on column C. Then from column C a drop down to column D which would produce another drop down to E.
Example: Waste"B" (Shingles) - Type "C" (25 yr) - Pds per area "D" (1.25) - Unit Amount "E" (sq). Once this is inputted the rest of my calculations should give me my required size of unit?
I upload an example sheet to help clear up my rambling.
Thanks in advance

You can use the indirect formula in the data validation in cell C5 =INDIRECT(SUBSTITUTE($A$2," ","_"))
Then use a vlookup for column d

See attached

Windy

Thanks Windy
That works great. I'm trying to play with excel and learn different formulas trying and by researching it. Sometimes I need a little help. Thanks to people like you, I've learned lots (in my mind) of things. Keep up the great support.
Regards