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. GROUNDWATER TECHNOLOGY, INC. <br /> STANDARD OPERATING PROCEDURE <br /> CONCERNING GROUNDWATER MONITORING <br /> SOP 8 <br /> Groundwater monitoring of wells at the site shall be conducted using an ORS Environmental Equipment <br /> (ORS) INTERFACE PROBE'"and SURFACE SAMPLER'".The INTERFACE PROBE,"is a hand-held, battery- <br /> operated device for measuring depth to petroleum product and depth to water as measured from an <br /> established datum (Le, top of the well casing which has ben surveyed). Separate-phase hydrocarbon <br /> (product) thickness Is then calculated by subtracting the depth to product from the depth to water. In <br /> addition, water elevations are adjusted for the presence of fuel with the following calculation: <br /> (Product Thickness) (0.8) + (Water Elevation) = Corrected Water Elevation <br /> Note: The factor of 0.8 accounts for the density difference between water and petroleum <br /> hydrocarbons. <br /> The INTERFACE PROBE TM consists of a dual-sensing probe which utilizes an optical liquid sensor and <br /> electrical conductivity to distinguish between water and petroleum products. A coated steel measuring tape <br /> transmits the sensor's signals to the reel assembly where an audible alarm sounds a continuous tone when <br /> the sensor Is Immersed in petroleum product and an oscillating tone when Immersed In water. The <br /> INTERFACE PROBE 'm Is accurate to 1/1 6th inch. <br /> A SURFACE SAMPLER'" shall be used for visual inspection of the groundwater to note sheens (difficult to <br /> detect with the INTERFACE PROBE 1, odors, microbial action, etc. <br /> The SURFACE SAMPLER'"used consists of a 12-inch4ong case acrylic tube with a Delrin ball which closes <br /> onto a cortical surface creating a seal as the sampler is pulled up. The sampler Is calibrated In Inches and <br /> centimeters for visual Inspection of product thickness. <br /> To reduce the potential for cross contamination between wells,the monitorings shall take place In order from <br /> the least to the most contaminated wells. Welds containing separate-phase hydrocarbons (free product) <br /> should be monitored last. Between each monitoring the equipment shall be washed with laboratory-grade <br /> detergent and double rinsed with distilled water. <br /> EE. GROUNDWATER <br /> ._. TECHNOLOGY, INC. <br />