Table 2 Skimmer types and the advantages and disadvantages of each Advantages Disadvantages Mechanical skimmers Floating No water is captured. Radius of influence covers small area. Can effectively skim thin (i.e. <50 mm) The slotted screen can become blocked. Large saucer layers of LNAPL. Only applicable to shallow LNAPL recovery. Small float Pneumatic pump Can effectively skim thin layers of LNAPL. Radius of influence covers small area. Durable pumps. The slotted screen and valves can become Adjustable (to minimise water captured). blocked. Needs to be adjusted (manually). Belt skimmer Can effectively skim thick layers of LNAPL. Belts have limited capacity; low removal Simple operation and maintenance. rates Passive skimmers Passive - canister Low cost Low recovery potential Simple operation and maintenance Absorbent bailer (or sock) Low cost Low removal rates Requires replacement
Table 2 Skimmer types and the advantages and disadvantages of each Advantages Disadvantages Mechanical skimmers Floating No water is captured. Can effectively skim thin (i.e. <50 mm) layers of LNAPL. Radius of influence covers small area. The slotted screen can become blocked. Only applicable to shallow LNAPL recovery. Large saucer Small float Pneumatic pump Can effectively skim thin layers of LNAPL. Durable pumps. Adjustable (to minimise water captured). Radius of influence covers small area. The slotted screen and valves can become blocked. Needs to be adjusted (manually). Belt skimmer Can effectively skim thick layers of LNAPL. Simple operation and maintenance. Belts have limited capacity; low removal rates Passive skimmers Passive - canister Low cost Simple operation and maintenance Low recovery potential Absorbent bailer (or sock) Low cost Low removal rates Requires replacement
Draft_AppGuide_K_Skimming.docx