January 1, 2003

From The Pumps Point of View - by John Hasslen

GOALS:

• Effective Collection of Leachate
• Long Life
• Leave Trash in the Landfill
• Minimum Head on Liner

1. Designing deep sumps allows pumps to run longer without increasing head on liner. The goal is to keep infiltration gallery as wet as possible.

2. Design sump inlet area for velocity of 0.1 foot per second. Slots are more effective in retaining small particles then round holes.

3. Design larger infiltration area around sump. Decrease velocity to one (1) foot per minute in the infiltration gallery.

4. Design guidelines should be taken from good water well design practices.

5. It has been proven in water well design that extended pump run cycles and low velocity reduce or delay incrustation and infiltration of fine solids.

6. Design using coarse filter pack around sump and then finer gravel around this to reduce infiltration.

7. Small sumps and infiltration gallery create greater changes in pressure (velocity) which increase precipitation.

8. The more often gallery is exposed, the more progressive the reduction of open area.

 

STEPS TO TAKE TO DELAY INCRUSTATION AND FOULING

1. Maximize possible inlet area to reduce velocity of flow through infiltration gallery and sump openings.

2. Reduce pumping rates to extend pumping period.

3. Use more then one sump to increase infiltration area and reduce velocity.

4. Periodic maintenance and cleaning.

5. Strictly enforce good construction practices. Use clean infiltration material of controlled size.

Sources

• “Water Well Handbook”, Keith E. Anderson - Published by Missouri Water Well and Pump Contractors Association, Inc.
• “Ground Water & Wells”  - Published by Johnson Division, UOP Inc.
• “Ground Water & Wells” 2nd Edition, Fletcher G. Driscoll  - Published by Johnson Division