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GROUNDWATER TECHNOLOGY <br /> STANDARD OPEP.&TING PROCEDURE <br /> CONCERNING GROUNDWATER MONITORING <br /> SOP a <br /> Groundwater monitoring of walls at the site shall be <br /> conducted using an ORS Interface Probe and Surface <br /> sampler. The Interface Probe is a hand held, battery <br /> operat, a device for measuring depth to <br /> etroleumand depth to water as measured from an establishedrdatum <br /> (i.e. , top of the well casing which has been surveyed) . <br /> Product thickness is then, calculated by subtracting the <br /> - depth to product from the depth to water. In addition, <br /> water elevations are adjusted for the presence of fuel <br /> With the following calculation: <br /> (Product Thickness) (.8)+(Water Elevation) <br /> a <br /> Corrected Water Elevation <br /> Note: The Factor of 0.8 accounts for the density <br /> difference between water and petroleum <br /> hydrocarbons. <br /> The Interface Pzobe consists of a dual sensing probe <br /> - Utilizing an optical liquid sensor and electrical con- <br /> ductivity to distinguish between water and petroleum <br /> prolucts. A coated steel measuring tape transmits the <br /> sensor'u signals to the re.tl assembly, where an audible <br /> alarm sounds a continuous tone when the sensor is <br /> immersed .in petroleum product and an Oscillating tone <br /> when immersed in water. The Interface Probe is accurate <br /> �+ to 1/16-inch. <br /> A Surface Sampler shall be used for visual inspection of <br /> the groundwater to note sheens (difficult to detect with <br /> the Interface Probe) , odors, microbial action, etc. <br /> k <br /> The Surface Sampler used consists of a 12-inch long cast <br /> acrylic tube with a Delrin ball which closes onto a <br /> conical surface creating a seal ss the sampler is pulled <br /> UP. The sampler is calibrated in inches and centimeters <br /> for visual inspection of product thi•;kness. <br /> To reduce the potential rot• cross"contamination between <br /> Wells the monitorings shall take place ir- order from the <br /> '.Oast to most contaminated wells, wells containing free <br /> product should be monitored last. Between each monitoring <br /> �- the equipment shall be washed with laboratory grade <br /> detergent and double rinsed with distilled water. <br /> r i,JCROUNMATER <br /> TwHsou)Gv.INC, <br />