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

B. ~ -66-Section 6. Well Location With Respecto Pollntants and Contaminants, and Structnres.ASe~aration. Cathodic protection wells shall be located an adequate distance from known orpotential sources of pollution or contamination, where site constraints and corrosion controlconsiderations allow. Potential sources of pollution and contamination include those listed inSection 8 of the Water Well Standards.As specified in Section 7 below, the length of the annular seal for a cathodic protection wellshall be increased if the well is located in a congested urban area, or is located within 100 feetof any potential source of pollution or contamination.Floodinl! and Drainage. Cathodic protection wells should be located in areas protected fromflooding, if possible. Wells located in areas of flooding shall be protected from flood watersand drainage, including protective measures outlined in Section 8, below.Ground surface surrounding a cathodic protection well shall slope away from the well.Drainage from areas surrounding a cathodic protection well shall be directed away from thewell.c. Accessibili!y. All cathodic protection wells shall be located an adequate distance from buildingsand other structures to allow access for well maintenance, modification, repair, and destruction,unless otherwise approved by the enforcing agency.Section 7. Sealing the Upper Annular Space.The space between the cathodic protection well casing and the wall of the well boring, often referred to as the"annular space," shall be effectively sealed to prevent it from being a preferential pathway for the movementof poor-quality water, pollutants, or contaminants. In some cases, secondary purposes of the annular seal areto stabilize the borehole wall, protect casing from degradation or corrosion, and ensure the structural integrityof the casing.General discussion of sealing requirements and methods is contained in Section 9, Section 13, and Appendix Bof the Water Well Standards. Special requirements for sealing cathodic protection wells are:AMinimum De~th of Annular Seal.1. Minimum DeRth. The annular space shall be filled with appropriate sealing materialfrom ground surface to a depth of at least 20 feet below land surface. The annularspace shall be sealed to a depth of at least 50 feet below land surface in congestedurban areas, or where a cathodic protection well is within 100 feet of any potentialsource of pollution or contamination. Additional annular sealing material shall beinstalled to greater depths where adverse conditions exist that increase the risk ofpollution or contamination of ground water.2. Bn. Any annular space existing between the base of the annular surface seal and thetop of the anode and conductive fill interval shall be filled with appropriate fill orsealing material. Fill material should consist of washed granular material such as sand,pea gravel, or sealing material. Fill material shall not be subject to decomposition or