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

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"8. 2.casing and the borehole wall other than the depths specified in Subsection A, above,and Section 13, below (page 46 of Bulletin 74-81)."Items 4 through 7 (page 32 of Bulletin 74-81) are unchanged. Item 8 has been added, as follows:Wells that enetrate zones containin oor- uali water ollutants or contaminants.If geologic units or fill known or suspected to contain poor-quality water, pollutants,or contaminants are penetrated during drilling, and, the possibility exists that poorqualitywater, pollutants, or contaminants could move through the borehole duringdrilling and well construction operations and significantly degrade ground water qualityin other units before sealing material can be installed, then precautions shall be takento seal off or 'isolate' zones containing poor-quality water, pollutants, andcontaminants during drilling and well construction operations. Special precautionscould include the use of temporary or permanent conductor casing, borehole liners,and specialized drilling equipment. The use of conductor casing is described in Item1, page 15, above."Subsection C (page 34 of Bulletin 74-81) is unchanged. Subsections 0, E, and F (page 34 of Bulletin 74-81)have been changed to read as follows:"D. Sealinl! Material. Sealing material shall consist of neat cement, sand cement, concrete, orbentonite. Cuttings from drilling, or drilling mud, shall not be used for any part of the sealingmaterial.1. ~. Water used to prepare sealing mixtures should generally be of drinking waterquality, shall be compatible with the type of sealing material used, be free of petroleumand petroleum products, and be free of suspended matter. In some cases waterconsidered nonpotable, with a maximum of 2,000 milligrams per liter chloride and1,500 mg/l sulfate, can be used for cement-based sealing mixtures. The quality of waterto be used for sealing mixtures shall be determined where unknown.Cement. Cement used in sealing mixtures shall meet the requirements of AmericanSociety for Testing and Materials C150, Standard Specification for Portland Cement,including the latest revisions thereof.Types of Portland cement available under ASTM C150 for general construction are:Type I -General purpose. Similar to American Petroleum Institute Class AType II -Moderate resistance to sulfate. Lower heat of hydration than Type I.Similar to API Class B.Type III -High early strength. Reduced curing time but higher heat of hydrationthan Type I. Similar to API Class C.Type IV -ExtendedType V -High sulfate resistance.. -17-setting time. Lower heat of hydration than Types I and III.Special cement setting accelerators and retardants and other additives may be used insome cases. Special field additives for Portland cement mixtures shall meet therequirements of ASTM C494, Standard Specification for Chemical Admixtures forConcrete, and latest revision thereof.
Hydrated lime may be added up to 10 percent of the volume of cement used to makethe seal mix more fluid. Bentonite may be added to cement-based mixes, up to6 percent by weight of cement used, to improve fluid characteristics of the sealing mixand reduce the rate of heat generation during setting.Dry additives should be mixed with dry cement before adding water to the mixture toensure proper mixing, uniformity of hydration, and an effective and homogeneous seal.The water demand of additives shall be taken into account when water is added to themix.Minimum times required for sealing materials containing Portland cement to set andbegin curing before construction operations on a well can be resumed are:.Types.Type.TypeI and II cement -24 hoursIII cement -12 hoursV cement -6 hoursType IV cement is seldom used for annular seals because of its extended setting time.Allowable setting times may be reduced or lengthened by use of accelerators orretardants specifically designed to modify setting time, at the approval of the enforcingagency.More time shall be required for cement-based seals to cure to allow greater strengthwhen construction or development operations following the placement of the seal maysubject casing and sealing materials to significant stress. Subjecting a well tosignificant stress before a cement-based sealing material has adequately cured candamage the seal and prevent proper bonding of cement-based sealants to casing(s).If plastic well casing is used, care shall be exercised to control the heat of hydrationgenerated during the setting and curing of cement in an annular seal. Heat can causeplastic casing to weaken and collapse. Heat generation is a special concern if thin-wallplastic well casing is used, if the well casing will be subject to significant net externalpressure before the setting of the seal, and/or if the radial thickness of the annular sealis large. Additives that accelerate cement setting also tend to increase the rate of heatgeneration during setting and, thus, should be used with caution where plastic casingis employed.The temperature of a setting cement seal can be lowered by circulating water insidethe well casing and/or by adding bentonite to the cement mixture, up to 6 percent byweight of cement used.Cement-based sealing material shall be constituted as follows:a. Neat Cement. For Types I or II Portland cement, neat cement shall be mixedat a ratio of one 94-pound sack of Portland cemento 5 to 6 gallons of 'clean'water. Additional water may be required where special additives, such asbentonite, or 'accelerators' or 'retardants' are used.b. Sand Cement. Sand-cement shall be mixed at a ratio of not more than 188pounds of sand to one 94-pound sack of Portland cement (2 parts sand to 1part cement, by weight) and about 7 gallons of clean water, where Type I orType II Portland cement is used. This is equivalento a '10.3 sack mix.' Less-18-
Page 1 and 2: --1#~Water wells .1Cathodic protect
Page 4 and 5: . ~~Bulletin 74-81)N. KennedyResour
Page 6 and 7: ~vState of CaliforniaPETE WILSON, G
Page 8 and 9: ~ viiForewordOrganization.TABLE OF
Page 10 and 11: ~ ix(4) Glass Fiber Reinforced Resi
Page 12 and 13: E~B. Sealing Conditions. 421. Tempo
Page 14 and 15: ~CATHODIC PROTECTION WELL STANDARDS
Page 16 and 17: 5.~Introduction:Figure 1.Years DWR
Page 19 and 20: GENERAL INTRODUCTIONImproperly cons
Page 21 and 22: Figure 1. YEARS DWR WELL STANDARDSB
Page 24 and 25: .9-REVISIONS TO WATER WELL STANDARD
Page 26 and 27: ~STANDARDSPart I. GeneralSection 1.
Page 28: ~B. c.-13-Many variables are involv
Page 34 and 35: d. ~c.water shall be used if less s
Page 36 and 37: 3. Foundation and Transition Seals.
Page 38 and 39: -23-otherwise approved by the enfor
Page 40 and 41: Thermoplastic well casing that may
Page 42 and 43: ~.Introducing.Combinationsspecifica
Page 44: ~-29-
Page 47: Advances in analytical and environm
Page 50 and 51: Nested monitoring wells consist of
Page 52 and 53: c.STANDARDSPart I.GeneralSection 1.
Page 54 and 55: 1.Part II.Monitoring Well Construct
Page 56 and 57: 1. 3.casing shall in turn be at lea
Page 58 and 59: c.Casing spacers shall be designed
Page 60 and 61: ~ 1.Section 12. Casing.The term "ca
Page 62 and 63: B. c. E.Over~um~ing and Pum~ Surgin
Page 64 and 65: 2. b.Section 19. Requirements for D
Page 66 and 67: 3. 5. E.freefall only where the int
Page 69 and 70: INTRODUCTIONMost wells in Californi
Page 72: Many cathodic protection wells have
Page 75 and 76: Need for Cathodic Protection Well S
Page 77 and 78: (Division 3, Chapter 9, California
Page 79 and 80: 3. B.E. c.consolidation after place
Page 81 and 82: for surface construction features a
Page 83 and 84:
~Part III.Destruction of Cathodic P
Page 85 and 86:
E.these standards, or standards ado
Page 88 and 89:
~APPEN DIX ADefinition of Terms-A m
Page 91:
National Association of Corrosion E
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California Water Well Standards, DWR Bulletin 74 ... - County of Glenn

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