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GROUNDWATER TECHNOLOGY, INC. <br /> STANDARD OPERATING PROCEDURE NO. 8 <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring of wells at the site shall be conducted using an ORS Environmental <br /> Equipment (ORS) INTERFACE PROBE"' or SURFACE SAMPLER' The INTERFACE PROBE' is a <br /> hand-held, battery-operated device for measuring depth to petroleum product and depth to <br /> water as measured from an established datum (r e., top of the well casing which has been <br /> surveyed) Floating separate-phase hydrocarbon (product) thickness is then calculated by <br /> subtracting the depth to product from the depth to water. In addition, water elevations are <br /> adjusted for the presence of floating product with the following calculation• <br /> i <br /> (Product Thickness) x (0.81 + (Water Elevation) = Corrected Water Elevation <br /> Note: The factor of 0 8 accounts for the density difference between water and <br /> t <br /> petroleum hydrocarbons <br /> The thickness of dense non-aqueous phase liquids (DNAPLs) is calculated by subtracting the <br /> depth at which the DNAPL is encountered from the total depth of the well Water-level <br /> elevations are not typically corrected for the presence of DNAPLs <br /> r <br /> The INTERFACE PROBE' consists of adual-sensing probe which utilizes an optical liquid Sensor <br /> and electrical conductivity to distinguish between water and petroleum products A coated <br /> steel measuring tape transmits the sensor's signals to the reel assembly where an audible alarm <br /> sounds a continuous tone when the sensor is immersed in petroleum product and an oscillating <br /> tone when immersed in water The INTERFACE PROBE' is accurate to 0 01 inch <br /> A SURFACE SAMPLER' shall be used for visual inspection of the groundwater to note sheers <br /> (difficult to detect with the INTERFACE PROBE"''), odors, microbial action, etc <br /> I The SURFACE SAMPLER' used consists of a 12-inch-long case acrylic tube with a Delrin ball <br /> which closes onto a conical surface creating a seal as the sampler is pulled up The sampler is <br /> calibrated in inches and centimeters for visual inspection of product thickness <br /> To reduce the potential for cross contamination between wells, the monitoring shall take place <br /> l in order from the least to the most contaminated wells Wells containing separate-phase <br /> hydrocarbons (free product) should be monitored last Between each monitoring the equipment <br /> shall be washed with laboratory-grade detergent and double rinsed with distilled water <br /> I <br /> CONCORD SOP CM4) <br /> GROUNDWATER <br /> 1 y�� TECHNOLOGY INC <br />