Update Aquifer Layers

[tbock]

Please investigate and report here.

At certain scales, the aquifers fail to draw. It is an intermittent issue. It is possible that converting to voxels will resolve this issue.

[froberts]

if you use the slides, or other time it seems as if the aquifers are not drawing and there is no feed back saying they are down loading.

[bsnider]

This is still happening intermittently. Brian was experiencing this issue, and couldn't zoom in and see layers.