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r Conestoga-Rovers & Associates Water Sampling Water samples, if they are collected from the boring, are either collected using a driven Hydropunch® type sampler or are collected from the open borehole using bailers. The groundwater samples are decanted into the appropriate containers supplied by the analytic laboratory_ Samples are labeled, placed in protective foam sleeves, stored on crushed ice at or below 4°C, and transported under chain-of-custody to the laboratory. Laboratory-supplied trip blanks accompany the samples and are analyzed to check for .cross-contamination. An equipment blank may be analyzed if non-dedicated sampling equipment is used. Grouting If the borings are not completed as wells, the borings are filled to the ground surface with cement grout poured or pumped through a tremie pipe. MONITORING WELL INSTALLATION, DEVELOPMENT AND SAMPLING Well Construction and Surveying Groundwater monitoring wells are installed to monitor groundwater quality and determine the _ .indwater elevation, flow direction and gradient. Well depths and screen lengths are based on _:,3.mdwater depth, occurrence of hydrocarbons or other compounds in the borehole, stratigraphy and State and local regulatory guidelines. Well screens typically extend 10 to 15 feet below and 5 feet above the static water level at the time of drilling. However, the well screen will generally not extend into or through a clay layer that is at least three feet thick. Well casing and screen are flush-threaded, Schedule 40 PVC. Screen slot size varies according to the sediments screened, but slots are generally 0.010 or 0.020 inches wide. A rinsed and graded sand occupies the annular space between the boring and the well screen to about one to two feet above the ell�ereen twofeet-{hick-hydrated-bentonite-seal-separates-the-sand- rom-tkeoverlyingsanitary surface seal composed of Portland type I, U cement. Well-heads are secured by locking well-caps inside traffic-rated vaults finished flush with the ground surface. A stovepipe may be installed between the well-head and the vault cap for additional security. The well top-of-casing elevation is surveyed with respect to mean sea level and the well is surveyed for horizontal location with respect to an onsite or nearby offsite landmark. Page 2 of 3