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J. H. KLEINFELDER & ASSOCIAS File: 5-1008-21/12 : 317 June 26, 1986 Page 4 Comments: 5. The proposed casing hammer/dual tube reverse circulations air rotary drilling procedure looks like a good method for logging the hole and identifying water-bearing zones. if foam is to be used, will the geologist on-site be able to identify the water-bearing zones? Air should be filtered to prevent oil from the compressor from entering the wells. Response: This method was suggested for the purpose of improved stratigraphic control and water yield information. Use of foam is not usually required, water yielding zones can generally be identified within 3-5 feet of their occurrence. The air rotary drill rig is equipped with an apparatus which filters the air from the compressor down to one micron. Comments: 6. Proposed materials for well construction are acceptable. Slotted pipe should be installed at least two feet above highest expected water levels. The sand backfill, bentonite pellets, and cement grout should be installed using a tremie pipe to prevent bridging. Will water be added to the bentonite pellets after placement or will they be mixed with a cement grout prior to placement? Filter pack design must be compatible with both the screen sizing and the geologic materials in the screened zone. Response: It is generally not advisable to tremie sand with the diameter of wells proposed. This is a procedure generally used in the construction of large diameter water wells. Bentonite and grout will be tremied as suggested. Water will be added to the bentonite pellets after placement. Filter pack design will be relatively compatible with the screen sizing and materials encountered. Our engineers have determined that #2 - *3 sands are suitable and compatible with 0.02 inch screen and most aquifer materials. Unless the conditions encountered are vastly different than the available information indicates, a *2 or *3 sand backfill will be used. In addition, well screen and well pack design is usually employed to maximum yield in water supply wells. Since the intent of the monitoring program is to ascertain water quality conditions, we can not find technical and economic justification for the additional cost of the design effort.