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Ms. Ann Kolata May 4, 2012 S61068.400.0001 Page 2 Hull will work with the drilling subcontractor and the appropriate City and St. Joseph County authorities to arrange for access for the work and to clear utilities and to prepare appropriate permits for drilling in the right -of -way. Drill cuttings and sample purge and decontamination water will be containerized and placed at a location designated by the City. Monitoring wells will be constructed of Schedule 40 PVC slotted screens and risers. Once the targeted depth has been reached, the well column will be slowly lowered to the base of the borehole. A clean silica quartz sand filter pack will be placed around the screen and will extend no more than two feet above the top of the screen. Sodium bentonite chips or pellets will then be placed on top of the sand pack. Above the chips or pellets, a thick bentonite slurry will be pumped into the annular space using a tremie pipe to a depth of approximately three feet below ground surface. The remaining three feet will be filled with concrete to anchor an above - ground (i.e., "stick -up ") protective casing (please note that these above - ground protective casings may be removed and replaced with flush -mount manhole covers if desired by the City in the future). Monitoring wells will be developed following installation to remove fines that may have entered the well screen or filter pack during installation. Well development activities will continue until pH, temperature, and conductivity have stabilized for three consecutive well volumes, or until five well volumes have been removed, whichever is greater. Development waters will be collected and stored in a DOT approved 55- gallon drum. Task 2 Soil Vapor Probe Installation The recent temporary groundwater sampling completed in April 2012 identified that groundwater exhibiting concentrations of chlorinated VOCs at concentrations exceeding groundwater to indoor air screening levels is leaving the Site at the northeastern boundary along Sample and Franklin Streets. To evaluate the necessity of installing monitoring wells off -Site, under the assumption that the groundwater to indoor air exposure pathway will likely drive any remedial and /or monitoring approach recommended in the forthcoming RWP, Hull recommends sampling soil gas above groundwater along Sample and Franklin Streets to evaluate whether any existing or future groundwater to indoor air exposure pathway is potentially complete. A total of eight soil gas samples, two from each of four locations, will be collected from points located generally along the rights -of -way of Sample and Franklin Streets in the northeast portion of the Site. The samples will be collected at approximate depths of six feet below ground surface (bgs) and 14 feet bgs, which is approximately four to six feet above the uppermost saturated unit at the Site. Soil gas sampling will not be conducted within 48 hours of a significant precipitation event ( >0.1 inches). The soil gas sampling point installation will be performed using a direct push drilling unit (i.e., GeoprobeTM unit). Soil borings will be logged continuously to a depth of approximately 14 feet at each location and screened with a photoionization detector (PID) during installation. Soil cuttings, acetate liners, gloves, etc. will be containerized in a drum onsite.