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Additional rLxluiremenLs for surface construction features are contained in Section 10 of the Water Well <br /> Standards, <br /> Section 9. Lasing. <br /> Vent pipe,anode access tubing, afln auyoiher rubular rnatcrials Thai pas.i tilrnu!'h rile InWiv,fi ELI nc; I11led and <br /> sealed are all considered casing for the purpose of Ihese standards. Materials used for cathodic protection well <br /> caging generally shall meet the requirements for casing materials and their installation in Section 12 of the <br /> Water W61 Standards. Variance from the standards shall be at the approval of the enforcing agency. It is <br /> recommended that practice.-, prescribed by the National AssociaifOn car`Unrosion Engineers alga be followed <br /> in the design and installation of gas vents and electrical conduit. <br /> [hodic protection well casing should be at least 2 inches in internal diameter to facilitate eventual well <br /> dertrui_lit�n, <br /> Section 10. Sealing-Off Strata. <br /> If a cathodic protection well penetrates a stratum or strata below the minimum required annular surface seal <br /> depth specified in Section 7,above and that stratum contains poor-quality water, pollutants,or contaminants <br /> that could mix with and degrade water contained in other strata penetrated by the well, additional annular <br /> sealing material shall be placed below the minimum required annular surface seal to prevent mixing and water- <br /> quality degradation. <br /> The following minimum requirements shall be observed for isolating zones containing poor-quality water, <br /> pollutants, or contaminants for various cases: <br /> Case 1. Upper Stratum. If a stratum containing poor-quality water, pollutants, or contaminants lies above <br /> a stratum to be protected,annular seal material shall extend from the top of the stratum containing the poor- <br /> quality water,pollutants,or contaminants down to at least 10 feet into the confining layer separating the two <br /> strata, or through the entire thickness of the confining layer,whichever is least. <br /> Case 2. Lower Stratum. If a stratum containing poor-quality water, pollutants, or contaminants lies below <br /> a stratum to be protected,the annular space opposite the stratum to be protected shall be sealed along its full <br /> length. The seal shall extend at least 10 feet into the confining layer separating the two strata,or through the <br /> entire thickness of the confining layer,whichever is least. <br /> Case 3. Multiple Strata. <br /> a. Where two or more strata containing poor-quality water, pollutants,or contaminants are adjacent to ' <br /> one another and overlie a stratum to be protected, the annular space opposite the strata containing <br /> poor-quality water, pollutants, or contaminants and opposite all interbedded confining layers shall be • <br /> sealed. The annular seal shall extend at least 10 feet down into, or completely through,whichever is <br /> least,the confining layer separating the strata containing poor-quality water,pollutants,or contaminants ' <br /> and the underlying stratum to be protected. <br /> b. Where two or more strata containing poor-quality water, pollutants, or contaminants underlie a • <br /> stratum to be protected, the annular space opposite the stratum to be protected shall be sealed. The <br /> seal shall continue down at least 10 feet into,or completely through,whichever is least, the confining • <br /> layer separating the stratum to be protected and the underlying strata containing poor-quality water, <br /> pollutants or contaminants. <br /> r <br /> -69- <br />