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„ casings. Once installation has begun, work will continue until the well has been <br /> grouted and the drill casing has been removed. <br /> �; • Well screens,casings, and fittings will conform to National Sanitation Foundation. <br /> Standard 14 or American Society for Testing and Materials (ASTM) equivalent for <br /> potable water usage. Material used will be new and essentially chemically inert to the <br /> site environment. <br /> • Filter pack will extend from the bottom of the screened section (top of aquitard)to a <br /> L height of 2 ft above the top of the screen. If the water table is relatively close to the <br /> ground surface,the filter pack may extend less than 2 ft above the screen to avoid <br /> surface water infiltration into the well and to allow for placement of the bentonite <br /> seal, grout, and protective casing. If the hole is less than 20 ft deep,the filter pack <br /> may be poured into the annulus directly. If the hole is deeper than 20 ft, the filter <br /> pack must be tremied into place. <br /> — Granular filter packs will be chemically and texturally clean,inert, and siliceous. <br /> — Filter pack grain size will be based on formation grain-size^analysis.. <br /> — Calculations regarding filter pack volumes will be entered into the Field Logbook <br /> along with any discrepancies between calculated and actual volumes used. If a <br /> discrepancy of greater than 10 % exists between calculated and actual volumes, an <br /> explanation for the discrepancy will,also be entered in the Logbook. <br /> • Bentonite seals-will be no less than one foot or more than three feet thick as measured <br /> immediately after placement. <br /> • Grout <br /> Grout used in construction will be composed by weight of approximately: <br /> C — 20 parts cement (Portland cement, type II)- <br /> - 0.6 to 1 part(max.)(3-5%) bentonite= 2.8 lbs to 4.7 lbs of bentonite to one 94 lb <br /> bag of cement <br /> — 6.5all - <br /> g ons approved water per 94 lb bag of cement. <br /> LNeither additives nor borehole cuttings will be mixed with the grout. Bentonite will <br /> be added after the required amount of cement is mixed with the water. <br /> • All grout material will be combined in an above-ground container and <br /> C <br /> mechanically blended to produce a thick lump-free e rruxture. Mixing of the grout <br /> will be performed by mixing the bentonite powder and water before adding <br /> Page 6 of 9 <br /> well—install—SOP MONITORING WELL INSTALLATION February 2005 <br /> i <br />