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� c7•'. _ � �' _ _ 31! '.4r`i'i� f y•V'a �° t i5 <br /> ^fi <br /> GROUNDWATER TECHNOLOGY <br /> BTANDARD OPERATING PROCEDURE <br /> CONCMWrNG ITER VIDW."MRINC <br /> sopa <br /> Groundwater monitorlM of wells at the site ca ll b:s <br /> conducted ms Ing an ORS Interface probe and Surface <br /> Baxapler. the Interface Probe is as band held, battery <br /> opex!aated device for measuring depth to petroleum product <br /> a.nd •depth to mater an measured frsm an established datum <br /> ' (i.e., top of the wall casing which has been surveyed) . <br /> Product thic)mesaa Is then calculated by subtracting the <br /> depth to product from the depth to water. In addition, <br /> water elevations se adjusted .or the presence of fuel <br /> with the following calculation; <br /> (product ThicJmeess) (.S)+(water Zlevation) <br /> - Corrected Nater Xlevation <br /> Hotde: The factor of 0.8 accounts for the density <br /> difference between water and petroleum <br /> hydrocarbons. <br /> The Interface Probe consists of a dual sensing probe <br /> utilizing an optical liquid sensor and electrical con- <br /> ductivity to distinguish between water and petrk*)leum <br /> products. A coasted steel measuring tape transmits the <br /> sensor's signals to the reel 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 crater. 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 /> The Surface Sampler used consists of ae 12-inch long cast <br /> acrylic tube with a Delrin ball which closes onto a <br /> conical surface creating a seal as the ssamprer is pulled <br /> up. The -sampler is calibrated In inches and centimeters <br /> for visual inspection of product thickness. <br /> To reduce the potential for cross contamination between <br /> wells the monitorings shall take place in order from the <br /> least to most contaminated wells. Wells containing free <br /> product should be monitored last. Between each monitoring <br /> the equipment sahrll be crashed With laboratory grade <br /> detergent and double rinsed with distilled water. <br /> 3 GRlll'�PK l7ER <br /> r J TEcw-uml,he <br />