Appendix H: Calculation of Required Cap Volumes for Level-Bottom Capping Projects

Appendix H

Calculation of Required Cap

Volumes for Level-Bottom

Capping Projects

The primary focus of this appendix is the calculation of the volume of cap-

ping material required for level-bottom capping projects, including the influence

of various operational considerations on required volumes. The information in

this appendix assumes a specific capping project has been identified, a disposal

site is available, the contaminated mound geometry (footprint, side-slopes, and

elevation) has been estimated, and the cap has been designed with respect to the

thickness of capping material required.

Capping Volumes for Circular

and Elliptical Mounds

From a plan view, capped mounds typically take either a circular or elliptical/

oval shape (Chapter 10, main text), so required cap volume calculations depend

on this shape. For a uniform cap thickness over the entire contaminated mound

surface (Figure H1), design must allow for inclusion of the cap volumes of the

inner flank, outer flank, and apron in the overall mound cap volume calculation.

This will be demonstrated in a generic example. If the cap thickness will be less

over the apron (Figure H2), then the cap volume calculation requires isolating

different sections of the cap for ease in calculation. For both cases, the volume

of cap material included in the apron must also be calculated as constructed

projects have shown this volume can be significant. Note that the following

relationships are unit independent (i.e., either English or SI may be used as long

as consistency is maintained).

For a uniformly thick cap on a circular mound (Figure H1), the following

methodology is given to calculate cap volume:

Appendix H Level-Bottom Capping Projects