In-situ Remediation/Product Recovery Technologies
Free Phase Product Skimming
GRS is the sole European distributor for Xitech skimmer pumps. Skimmer pumps, controllers and ancillary products can be purchased directly from GRS or through our agent in Mainland Europe, FWS Filter-und Wassertechnik (also a Parent Company of GRS Ltd.)
Xitech skimmer pumps are capable of recovering free product ranging from lubricating oil to diesels and petrol at temperatures up to 70°C and 400 mBar vacuum conditions (Vacuum Enhanced Product Recovery). The skimmers require no above ground controls and have up to 1.5 metres of float travel.
The skimmers utilise a dual-entry hydrophobic filter and remove product down to a sheen at a rate of up to 2 litres/minute. Due to an extremely low air consumption rate of 14 litres/minute (max) they can operate on bottled nitrogen gas. The pumps are intrinsically safe and can be installed in less than 1 hour.
Models are available for 2" wells, 4" wells, for heavy oil and for high temperature steam enhanced applications. All Xitech pumps can operate under vacuum. There is also a range of Xitech pumps for dense phase solvents including chlorinated hydrocarbons and coal tar.
We can offer three electronic timer controllers for the operation of skimmer pumps. The key for operation of a skimming pump where hydraulic control with submersible pumps is not simultaneously conducted is to operate on a timed basis.
Where for example a recovery well has 1 metre of free-phase LNAPL, continuous pumping of the LNAPL is not the most effective modus operandi. On the contrary, continuous removal of the product from the well allows the water level to rebound to its natural level effectively forming a barrier against product outside the well flowing into the well. This can displace oil within the soils such that the soil becomes "water wet". LNAPL flows less readily through "water wet" soils.
At commissioning, the operator should measure the time required to pump out circa 90% of the LNAPL from the well and the time for the product to recover to circa 90% of its original thickness. The on/off period of the timer should then be set accordingy. This may be 10 minutes or 1 week. In this way, the formation around the recovery well is more likely to remain "oil-wet" thus facilitating a more ready flow LNAPL into the well. Site evidence has demonstrated that product recovery rates can literally double through this approach.
Download adobe acrobat version
Soil Vapour Extraction/Air Sparging
Dual-Phase (High Vacuum) Extraction
Multi-Phase (High Vacuum) Extraction
Product Recovery Technologies
Aqueous-Phase Activated Carbon
Air Strippers and Vacuum Strippers
Filters/Settlement/Oil-Water Separation/Ion Exchange
Vapour Phase Activated Carbon