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Nolte and Associates Inc. • • c MONITORING WELLS Locations of well screens will be in accordance with the drawings or per the direction of the Engineer. Well centralizers, if deemed necessary by the Contractor to maintain appropriate plumb, shall be PVC and shall be attached to the casing using stainless steel. C. Grout and Seal Grout will be composed by weight of 10 parts Portland cement to 1/2 part bentonite, with a maximum of 10 gal of approved water per 94 lb bag of cement. Bentonite will be added after mixing of the cement and water. Bentonite pellets used in the seal will be a commercially available product designed for well sealing. Bentonite sealing material above the gravel pack shall be high quality bentonite clay as manufactured by Volclay or equal. D. Gravel Pack Gravel pack shall be sand composed of sound durable particles and shall be free of organic matter, clay balls, and other deleterious substances. Sand material used in the pack around the well screen will be selected to be compatible with both the screen slot size and aquifer materials. Gravel pack for the monitoring wells shall have an approximate Dlo of 0.02 in. This size may be changed depending on the results of the formation sample sieve analysis. The pack shall have a uniformity coefficient less than 2.5. The pack shall be properly cleaned and bagged by the supplier. A sample of the pack material proposed to be used, with sieve analysis, shall be submitted to the Engin or ap rov obtained in writing before any�ack material is delivered to the well sites. E. Protective Casing, Load Rated Well Box/Cover, Well Access A 10 in. protective steel casing will be installed around each well. This protective casing will extend approximately 2 ft above land surface and will be seated 3 ft into the well seal grout. The protective casing will be vented to the atmosphere by a lockable, hinged cap. This cap will prevent entry of water but will not be airtight. In this manner, the well will be in open connection to the atmosphere to allow for water level stabilization. In addition, a 1/4 in. diameter drainage port will be installed centered 1/8 in. above the level of the concrete pad. The top of the well casing will have a removable Sch 40 PVC oversized cap to prevent well contamination. Contractor shall furnish heavy duty padlocks, Master, American, or equal for all monitoring wells. The same key will be used for all monitoring well padlocks at the site. 4