California Water Well Standards, DWR Bulletin 74 ... - County of Glenn

for surface construction features are contained in Section 10 of the Water WellMaterials used for cathodic protection wellthe requirements for casing materials and their installation in Section 12 of theVariance from the standard shall be at the approval of the enforcing agency. It is.-0 -,C .installation of gas vents and electrical conduit.protection well casing should be at least 2 inches in internal diameter to facilitate eventual wellSection 10. Sealing-Off Strata.If a cathodic protection well penetrates a stratum or strata below the minimum required annular surface sealdepth specified in Section 7, above and that stratum contains poor-quality water, pollutants, or contaminantsthat could mix with and degrade water contained in other strata penetrated by the well, additional annularsealing material shall be placed below the minimum required annular surface seal to prevent mixing and waterqualitydegradation.The following minimum requirements shall be observed for isolating zones containing poor-quality water,pollutants, or contaminants for various cases:Case 1. UDDer Stratum. If a stratum containing poor-quality water, pollutants, or contaminants lies abovea stratum to be protected, annular seal material shall extend from the top of the stratum containing the poorqualitywater, pollutants, or contaminants down to at least 10 feet into the confining layer separating the twostrata, or through the entire thickness of the confining layer, whichever is least.Case 2. Lower Stratum. If a stratum containing poor-quality water, pollutants, or contaminants lies belowa stratum to be protected, the annular space opposite the stratum to be protected shall be sealed along its fulllength. The seal shall extend at least 10 feet into the confining layer separating the two strata, or through theentire thickness of the confining layer, whichever is least.Case 3. Multiole Strata.a. Where two or more strata containing poor-quality water, pollutants, or contaminants are adjacent toone another and overlie a stratum to be protected, the annular space opposite the strata containingpoor-quality water, pollutants, or contaminants and opposite all interbedded confining layers shall besealed. The annular seal shall extend at least 10 feet down into, or completely through, whichever isleast, the confining layer separating the strata containing poor-quality water, pollutants, or contaminantsand the underlying stratum to be protected.b. Where two or more strata containing poor-quality water, pollutants, or contaminants underlie astratum to be protected, the annular space opposite the stratum to be protected shall be sealed. Theseal shall continue down at least 10 feet into, or completely through, whichever is least, the confininglayer separating the stratum to be protected and the underlying strata containing poor-quality water,pollutants or contaminants.-69-