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' zone at the site. Available subsurface information was utilized <br /> in the selection of the grain size. The gravel pack was selected <br />' such that it will permit the development of a zone of higher <br /> hydraulic conductivity adjacent to the well screen but will not <br /> allow piping of the finer-grained formation into the well bore. <br />' The slot size of the well screen was selected such that it will <br /> retain a minimum of 95% of the gravel pack material . <br /> 1.5 Monitoring Well Development <br /> Each monitoring well was developed after construction with a 5- <br /> inch-diameter stainless steel bailer until the water produced was <br /> ' relatively sediment-free. No water or chemicals were introduced <br /> into the monitoring wells during well development. All developed <br /> water was placed in drums on site for later disposal . <br /> I1. 6 Ground Water_ Sampz_inQ <br /> A minimum of 24 hours following well development, and after water <br /> ' levels were allowed to stabilize in the well , three to five <br /> wetted casing volumes of liquid were removed from each well by <br /> bailing with a laboratory-cleaned dedicated disposable bailer. A <br /> ' liquid sample was then collected from each well with a <br /> laboratory-cleaned, dedicated disposable bailer. Each sample was <br /> appropriately labeled and stored on ice from the time of <br /> collection through the time of delivery to the laboratory. <br /> ' Ground water samples were transported to the laboratory and <br /> analyzed within the EPA-specified holding times for the requested <br /> analyses. <br /> 1.7 Quality- Assurance Plan <br /> 1.7 .1 General Sample Collection and Handling Procedures <br /> Proper collection and handling are essential to ensure the <br /> quality of a sample. Each sample was collected in a suitable <br /> container, preserved correctly for the intended analyses, and <br /> stored prior to analysis for no longer than the maximum allowable <br /> holding time. Details on the procedure for collection and <br /> handling of soil samples used on this project can be found in the <br /> Methods Section 1 . 1. <br /> 1.7 .2 Sample Identification and chain-of-Custody Procedures <br /> ' Sample identification and chain-of--custody procedures ensure <br /> sample integrity and document sample possession from the time of <br /> collection to its ultimate disposal . Each sample container <br /> submitted analysis had a label affixed to identify the fob <br /> number, date, and time of sample collection, and a sample number <br /> unique to that sample. This information, in addition to a <br /> description of the sample, field measurements made, sampling <br /> methodology, names of on-site personnel , and any other pertinent <br /> field observations was recorded on the borehole log in the field <br /> ' records. All samples were analyzed by a state-certified <br /> laboratory. <br /> ' A chain-of-custody form was used to record possession of the <br /> sample from time of collection to its arrival at the laboratory. <br /> When the samples were shipped, the person in custody of them will <br /> ' relinquished the samples by signing the chain-of-custody form and <br />