Design Guide for Community Water Systems - The Water, Sanitation ...

second. Lower entrance velocity is recommended for water ofsignificant incrustating potential;d. Be installed so that the pumping water level remains above thescreen under all operating conditions;e. Where applicable, be designed and installed to permit removal orreplacement without adversely affecting watertight construction ofthe well;f. Be provided with a bottom plate or washdown bottom fitting of thesame material as the screen; andg. Be capable of resisting the column and tensile loads and thecollapse pressures imposed during installation and welldevelopment and imposed by the external geological forces.3.2.5.10. Plumbness and alignment requirements.a. Every well shall be tested for plumbness and alignment inaccordance with the latest edition of AWWA Standard A-100.b. The test method and allowable tolerance shall be clearly stated inthe specifications.c. If the well fails to meet these requirements, it may be accepted bythe engineer, after consultation with the department, if it does notinterfere with the installation or operation of the pump or uniformplacement of grout.3.2.5.11. Grouting requirements.a. All permanent well casings shall be surrounded by a minimum of1½ inches of grout to the depth required by the department.Grouting consists of filling the annular space between thepermanent casing and the drill hole with impervious material.Grouting is necessary to protect water-bearing aquifers fromcontamination, to prevent unwanted water movement betweenaquifers and to preserve or protect the hydraulic response of thewater producing zones.b. Grout materials shall consist of Portland cement conforming to thelatest AWWA Standard and water, with not more than six gallonsof water per sack (94 pounds) of cementc. Additives may be used to increase fluidity of grout materials or tobridge voids, subject to prior approval by the department.d. Application.1. Sufficient annular opening shall be provided to permit aminimum of 1 1/2 inches of grout around permanentcasings, including couplings.2. Prior to grouting through creviced or fractured formations,bentonite or similar materials may be added to the annularopening, in the manner indicated for grouting.3. Before placing the grout, water or other drilling fluid shallAug. 29, 2003Page 38