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Organic Vapor Procedures Soil samples will be collected at five-foot depth intervals for analysis in the field for ionizable organic compounds using a PID with a 10.2 eV lamp. The test procedure involves measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a ZiplockTM-type bag or in a clean glass jar, and sealing the jar with aluminum foil secured under a ring-type threaded lid. The container will be warmed for approximately 20 minutes (in the sun); then the head-space within the container will be tested for total organic vapor, measured in parts per million as benzene (ppm; volume/volume), The instrument will be calibrated prior to drilling. The results of the field-testing will be noted on the boring logs. PID readings are useful for indicating relative levels of contamination, but cannot be used to evaluate petroleum hydrocarbon levels with the confidence of laboratory analyses. Well Installations and Groundwater Monitoring Well Development Groundwater monitoring wells are constructed by inserting or tremming well materials through the annulus of the casing. In general, groundwater monitoring wells are constructed with 10 feet of screen below groundwater and 10 feet above groundwater, for a total screen length of 20 feet. Where shallow groundwater is encountered or perched water dictates otherwise, the screen is adjusted as appropriate, to maintain a proper seal at the surface (minimum three feet) and to avoid penetrating low permeable horizons or aquicludes. Groundwater wells are installed in accordance with the conditions of the well construction permit issued by the regulatory agency exercising jurisdiction over the project site. • The well screen generally consists of schedule 40 polyvinyl chloride (PVC) casing with 0.01 to 0.02 factory slots. As a general rule, 0.01 inch slots are used in fine-grained silts and clays, and 0.02 inch slots are used in coarse-grained materials. The screen is then filter packed with#2112 or#3 sand, or equivalent, for the 0.01 and 0.02 inch slots, respectively. Once the borehole has been drilled to the desired depth, and the tremmied grout has set at the bottom of the boring (in the case of deeper borings), approximately six inches of filter sand are tremmied to the bottom of the boring. The well screen and blank well casing are then inserted through the annulus of the casing. The well screen is sandpacked by tremming the appropriate filter sand through the annulus. During this operation, the depth of the sand pack in the auger is continuously sounded to make sure that the sand remains in the annulus to avoid shortcircuiting the well. The sand pack is tremmied to approximately two feet above the screen, at which time pre-development surging is performed to consolidate the sand pack. Additional sand is added as necessary so that the sand pack extends a minimum of two feet above top of the screen. Following construction of the sand pack, a two foot thick bentonite seal is tremmied over the sand and hydrated in place. The remainder of the borehole is backfilled with bentonite grout, pellets, or chips. The well head is then capped with a locking cap and secured with a lock to protect the well from surface water intrusion and vandalism. The well head is further protected from damage with traffic a rated well box in paved areas or locking steel riser in undeveloped areas. The protective boxes or risers are set in concrete. The details of well construction are recorded on well construction logs.