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OEM-- <br /> E- <br /> ll <br /> b. <br /> GROUNDWATER TECHNOLOGY <br /> 3 y' STANDARD OPERATING PROCEDURE <br /> CONCERNING GROUNDWATER MONITORING <br /> SOP S <br /> Groundwater monitoring of wells 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 /> operated device for measuring depth to petroleum product <br /> and depth to water as measured from an established datum <br /> (i•e. o top of the well casing which has been surveyed) . <br /> Product thickness is then calculated by subtractixig 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) (.S)+(Water Elevation) <br /> a Corrected Water Elevation <br /> Noter The factor of 4.8 accounts for the density <br /> difference between water and petroleum <br /> ti <br /> hydrocarbons. <br /> The Interface Probe consists of a dual sensing robe <br /> utilizing an optical liquid sensor and electrcal .con- <br /> ductivity to distinguish between water and petroleum <br /> i products. A coated steel measuring tape .transmits the <br /> sensor's signals: to the reel assembly, where an audible <br /> alarm sounds .a continuous tore when the sensor is I <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 /> f A Surface Sampler shall be used for visual inspection of <br /> p, f . .... the groundwater to note sheens (difficult to detect with <br /> the Interface Probe) , odors, microbial action, etc. <br /> The Surface Sampler used consists of a'12-inch long cast <br /> Z, acrylic tube with a Delrin .ball .which•closes onto a <br /> conical surface creating-_a_seal-,as the:_sampler-is. pulled <br /> up -The sampler is calibrated in inches and centimeters - <br /> F° for visual inspection of product;thickness, <br /> �. To reduce the potential for cros. contamination between <br /> wells the monitorings shall take °ace in order from the <br /> least to most .contaminated`wells. Wells containing free <br /> product should be monitored last. Be.tvieen each monitoring <br /> { the equipment shall be washed with laboratory grade <br /> detergent and double rinsed with distilled water. <br /> 11 . <br />