Dry tons = Wet tons × percent solids 100 Dry tons = gal × 8.34 2000 × percent solids 100 Note: For septage assume 2% solids . Conversion e xample: biosolids cake . If you have 32 tons of wet biosolids cake at 16.5% solids, use the first formula above to determine dry tons: Wet tons × %Solids/100 = Dry tons 32 Wet tons× 16.5 100 = Dry tons ...