Each month Tim Stark introduces a new technical topic for discussion and possible action. This month’s topic is: “Determining Lining/Floating Cover Systems for Critical and Non-Critical Applications”. This topic generated significant discussion with the main “take-aways” being listed below:
Non-Critical Applications
· Relevant Factors/Questions:
- Site Specific Determination – Activate ancient landslide or fault system? If so, critical application
- Does the owner accept some leakage?
- Regulations don’t require zero leakage?
- What is the cost of a leak (environmentally or economically)?
- What is allowable (regulation)/acceptable (owner) leakage rate?
- What is subgrade condition? Soft, hard, existing asphalt, existing concrete, does it need remediation? If so, may be critical application
- What is geomembrane being selected?
- Site specific CQA/CQC requirements – depends on GM selected but usually less than critical applications
- Is site specific Leak Location Testing necessary? – depends on site
- Choice of material depends on availability, e.g., available soil v. GM
· Non-Critical Applications:
- Canal liners
- Temporary remediation
- Decorative ponds
- Landscape ponds
- Detention basins – control flow
- Stormwater collection – depends on level of contamination – natural and man-made
- Wetland mitigation
- Dewatering
- Freshwater containment if water is readily available
- Final cover systems
- Floating cover system for non-potable water – site specific
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