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FINAL • DDRW a Well Installation Work Plan 2.4 Location SurveVing with 4-1/4-inch internal diameter hollow stem augers to obtain a continuous core for lithologic Once installed, the proposed wells and logging. Drilling and sampling will occur piezometer will be surveyed according to according to the procedures outlined in the procedures outlined in the Comprehensive Field Comprehensive Field Work Plan.Final well Work Plan.Location surveying for 72 existing boring diameters have not yet been determined; landmarks, including wells, the three prior to monitoring well or piezometer groundwater treatment plants, and canals,has construction,the borings may be reamed with also been recommended(see Attachments 1 larger diameter augers to provide sufficient and 2). annular space for construction. 2.5 Monitoring Well Abandonment 3.1.3 Air Rotary Casing Hammer. The C and D aquifer zones are composed of semi- Abandonment is recommended for 35 existing consolidated and discontinuous layers and wells (Figure 2-1).Abandonment procedures lenses of sand,silt, and clay,including 5 to 12 should be performed according to the general feet thick sand layers. Borings for C and D zone procedures described in the Comprehensive monitoring wells and piezometers will be drilled Field Work Plan. with an Air Rotary Casing Hammer according to the procedures described in the Comprehensive 2.6 Well Maintenance Field Work Plan. Boring diameters have not yet been determined. Maintenance of 133 existing monitoring, extraction, and dewatering wells is 3.2 Lithologic Logging recommended for this field effort(Figure 2-1). Maintenance will consist of repairing damaged During the drilling of the boring for each surface completions and well pads,and monitoring well or piezometer, an accurate log replacing locks and identification tags. should be maintained by the field geologist.At a minimum,the log should include: 3.0 MONITORING WELL AND OBSERVATION PIEZOMETER • Name of the project and site; BORING DRILLING • Boring number; 3.1 Drilling Methods • Dates drilled; 3.1.1 The proposed monitoring wells and • Location of the boring; piezometer cluster will be drilled into one of the • Type of drill rig; four aquifer zones (designated A,B,C,D). The four zones are not laterally continuous or at a • Size and type of drilling method used; consistent depth across the installation. The top depths of the A,B,C,and D zones average 10, • Depth at which groundwater was fust 40,90,and 170 feet below ground surface encountered; (BGS),respectively. • Depth to the static water level and changes 3.1.2 Hollow Stem Auger.The A and B in static water level with boring depth; aquifer zones consist of alluvial deposits in • Total depth of the boring; discontinuous layers and lenses,including 5 to 12 feet thick sand layers.Eight-to 9-inch Depth or location of any problems diameter borings for A and B zone monitoring encountered (i.e., running sands); wells and piezometers will initially be drilled • Lithologies of soil layers encountered; S-SSWP.DOC 5 September 1996