ARCHIVED REPORTS XR0012566 - Laserfiche WebLink

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r- ;�,. fir, :� � R• w�..�"" `".,er r '��, ,�` ,r ,x„ .� .�- .+ i". "�--; ��, ,� - '.� ��:�^`,..,�:, 5 The monitor well's are cased with 2-inch diameter threaded,factory-perforated and blank Schedule 40 PVC pipe. The perforated interval consists of slotted casing,eenerally 0.020-inch wide by 1.5-inch long slot size,with 42 slots per foot. Selection of slot size and filter material will be based on standard design criteria. The slotted/perforated interval will be gravel or sand packed to a minimum of 2 feet above die uppermost slot or perforation; the placement of the uppermost slot or perforation will reflect anticipated f,o� Y fluctuations in the water table. Based on site lithology,tbLWeiUnsf�eoltot;will uire th' the slotting be extended up to the mid-tank level. A thr^•aded PVC cap is faswriedff the 'bottomof the casing. Centering devices may be faster,cei to the casing to assure even diatiibution'of filter material and grout within the bomhole annulus. The well casing is cleaned prior to installation and will be constructed of clean,inert material. No slotting.Will be allowed to connect twgmtatit.4y.penrteable lenses which appear to be S rusted.by-a slidVOY ffiReae zoite rI Outthe express approval of the«ell' �psp i Tlie well will he completed such that the top of the screen is positioned above t-fie-anticipated seasonal high Ievel of groundwater. The well casing will be held in tension during consti action by suspending the casing above the bottonn-i the 1 ole during the gravel pack and seal installation. After setting the casing inside the hollow ste..a,sand or gravel filter material is poured into the annular space to fill from the bottom of the boring to 2 feet above the perforated interval. Surging with a surge block may be done to prevent sand bridging prior to adding the bentonite. +� A one to two foot thick bentonite plug(spacer)is placed above the filter material to prevent the grout from infiltrating down into the filter material. Neat pordand cement, containing about 5%bentonite,is then poured or tremied into the annular space from the top of the bentonite plug to the surface. he sealing material shall be a neat cement grout composed of one sack of Portland Type I/II Cement(941bs.}to five gallons of clean v water or a s f cement slurry with a minimum of eleven sacks of Portland type I/II 1 cement per cubic yard. If standing water.is present or if there is more than a 30 foa length to,he sealed;the sealing material shall be placed by means of a tremie pipe lowered to within three feet of the underlying layer of material or bottom of the well. The sealing material shall be placed in one continuous operation until the specified interval or borehole is filled. If a tremie pipe is used,the end of the tremie pipe shall remain in place in the sealing material until placement is complete. A lockable PVC cap is placed on each wellhead. Traffic-rated flush-mounted steel covers are installed around wellheads for wells in parking lots and driveways,while steel stove pipes are usually set over wellheads in landscaped areas. See Figure 4 for generalized well design. The surface of the monitoring well will be protected from fluid entry, accidental damage,unauthorized access and vandalism. The cover of the well will be clearly marked, Monitor well". A small metal tag or permanent marking containing the well number and summarized construction data such as depth,hole and casing diameters and location of the screened interval will be permanently attached to the well or placed within the vault and secured to the well-head. WELL DEVELOPMENT After installation,the wells are thoroughly developed to remove residual drilling materials <4 from the wellbore,and to improve well performance by removing any fine material in the filter pack that can pass from the formation into the well. Well development techniques include pumping,bailing,surging,swabbing,jetting,flushing and airlifting. All