SUB-PROBLEMS INCLUDING LEADING TO IMPAIRMENT AND BEST PRACTICES FOR SURFACE IMPOUNDMENTS USED FOR MANAGING HAZARDOUS WASTES
(See endnote 92)
A surface hazardous waste impoundment is like a hazardous waste landfill cell. It is placed in a natural depression or an excavation in the soil with a dike area. It has to be lined with a special double liner, which will be discussed separately. It must also have a leachate collection and removal system which is located between the liners immediately above the bottom composite liner, along with a leak detection system. The bottom slope of the impoundment must be made of materials that are chemically resistant to the waste and flow downward to a sump pump to pump out the liquids. With permission of the authorizing authority and no leaks in the existing surface of the hazardous waste impoundment, the use of an existing single liner may be accepted.
Best Practices for Surface Impoundments Used for Managing Hazardous Waste
- • Follow all information and Best Practices utilized for hazardous waste landfills.
- • All earthen dikes must have a protective cover such as grass, shale, or rock to reduce problems from wind and water erosion and maintain structural integrity.
- • Waste analysis and trial tests must be run on all waste being brought to the surface impoundment. If necessary, the hazardous waste needs to be treated chemically before it can be put within the unit.
- • At closure, all waste residues must be decontaminated including the containment system, contaminated subsoils, equipment, and supplies.
- • All free liquids must be solidified and then removed as waste or waste residues.
- • Establish a long-term program for minimizing migration of any liquids that may be left in the closed impoundment.
- • Maintain the integrity of the unit, as well as monitor the leak detection system.