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_+p7' �1�+.'�•�.fiS.'�i, wry .� .F-w �s t' �,y- x �y�{t,..' Y'a ,.r� � "`��.. ' ""�. 'y - � �'� _ �' '+ �we ��=` ' :S w, e. t 1.4 Monitoring Well Gravel Pack and Slot Size Selection The size of the gravel pack that were placed adjacent to the well screen will be determined by the project manager based on an estimation of the grain size distribution of the formation within the uppermost saturated zone at the site. Available geologic information was utilized in the selection of this grain size. The gravel pack was selected such that it wilt permit the development of a zone of higher hydraulic conductivity adjacent to the well screen but will not allow piping of the finer-grained formation into the well bore. The slot size of the well screen was selected such that it will retain a minimum of 95 percent of the gravel pack material. 1.5 Mnnitorine Well Development After monitoring wells were installed,each monitoring well was developed after construction with a 1.75- inch-diameter manual pump until the water produced was relatively sediment-free or until measurements of pH, specific conductance, and temperature stabilized. If the well was pumped dry during the developmzmt process, recharge rates will be recorded. No water or chemicals were introduced into the monitoring wells during well development. All developed water was placed in drums and stored on site for later disposal. 1.6 Ground Water Samoline A minimum of 24 hours following well development,and after water levels had been allowed to stabilize in each well, three to five wetted casing volumes of liquid was removed from each well by bailing with a laboratory-cleaned teflon bailer. :Measurements of pH,specific conductance,and temperature had been made at regular intervals during this procedure. Removal of liquid from each well was continued until the measurement ,pH, specific conductance, and temperature had stabilized. A liquid sample was then collected from each well with a;few,disposable teflon bailer. I-'.ch sample was appropriately labeled and stored on ice from the time of collection through the time of delivery to the laboratory. Ground water samples were transported to the laboratory and analyzed within the EPA-specified holding times for the requested analyses. 1.77 Petroleum Product If ftee petroleum product. was present in a well, the thickness of the product layer was measured by application of a product,water interface probe. A sample of the product was collected with a Eabaraton- cleaned teflon bailer aad transferred to an appropriate sample container and subsequently submitted to a Califurnia-certified laboratory for fuel fingerprint analysis.