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

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1.Part II.Monitoring Well ConstructionSection 8. Well Location With Respect to Pollutants and Contaminants, and Structures.Monitoring wells are usually constructed to observe conditions at defined or required locations. Monitoringwell locations are usually selected on the basis of known or expected hydrologic, geologic, and water qualityconditions and the location of pollutant or contaminant sources. Monitoring wells frequently need to belocated close to or within areas of pollution or contamination.ASe~aration. Monitoring wells shall be located an adequate distance from known or potentialsources of pollution and contamination, including those listed in Section 8 of the Water WellStandards, unless regulatory or legitimate data requirements necessitate they be located closer.B. Flooding and Drainage. Monitoring wells should be located in areas protected from flooding,if possible. Provisions for locating monitoring wells in areas of flooding and drainage arecontained in Section 8 of the Water Well Standards.c. AccessibilitY. All monitoring wells shall be located an adequate distance from buildings andother structures to allow access for well maintenance, modification, repair, and destruction,unless otherwise approved by the enforcing agency.D. Disposal of Wastes When Drillinl! in Contaminated or Polluted Areas. Drill cuttings andwastewater from monitoring wells or exploration holes in areas of known or suspectedcontamination or pollution shall be disposed of in accordance with all applicable federal, State,and local requirements. The enforcing agency should be contacted to determine requirementsfor the proper disposal of cuttings and wastewater.Section 9. Sealing the Upper Annular Space.The space between the monitoring well casing and the wall of the well boring, usually 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, and contaminants. Since monitoring wells are often constructed to obtainwater from discrete intervals, a secondary purpose of the annular seal can be to isolate the well intake sectionor screen to one water-bearing unit. The annular seal can also serve to protect the structural integrity of thewell casing and to protect the casing from chemical attack and corrosion. Because monitoring wells are oftenlocated close to, or within areas affected by pollutants and contaminants, an effective annular seal is oftencritical for the protection of ground water quality.General discussion of sealing methods and requirements for monitoring wells is contained in Section 9,Section 13, and Appendix B, of the Water Well Standards. Special requirements for monitoring wells includethe following:AMinimum DeQth of Annular Seal.Water Qualitv monitorinl! wells and monitoring wells constructed in areas of known orsusp;ected p;ollution or contamination. The annular space shall be sealed from the topof the filter pack or monitoring zone to ground surface, unless otherwise approved bythe enforcing agency. The top of the filter pack or monitoring zone shall not extendinto another water-bearing unit above the single water-bearing unit being monitoredunless otherwise approved by the enforcing agency. The filter pack or monitoring zoneshall not extend into any confining layers that overlie or underlie the unit to be moni--41-
3. .6.tored, unless otherwise approved by the enforcing agency. The annular surface sealshall be no less than 20 feet in length. 8'Seal lengths less than 20 feet are permissible only if shallow zones will be monitoredand approval has been obtained from the enforcing agency. If possible, specialprotection shall be provided where a reduced-length seal is used, as described in Section8 of the Water Well Standards.2. Other Monitoring Wells. The upper annular seal shall extend from ground surface toa minimum depth of 20 feet. An annular seal less than 20 feet in length is permissibleif provisions in Item 1, above, are followed.Sealinl! Off Strata. Additional annular sealing material shall be placed below theminimum depth of the upper annular seal, as is needed, to prevent the movement ofpoor-quality water, pollutants, and contaminants through the well to zones of goodqualitywater. Requirements for sealing off zones are in Section 13 of the Water WellStandards.4. Shallow Water Level Observation Wells. Water level observation wells less than 15feet in total depth that are used to assess root zone drainage in agricultural areas areexempt from an annular surface seal requirement, unless otherwise required by theenforcing agency.5. Areas of Freezing. The top of the annular seal may be below ground surface in areaswhere freezing is likely. Such areas include those listed in Section 9 of the Water WellStandards. The top of the annular seal shall not be more than 4 feet below groundsurface. The remainder of the space above the seal may be made an integral part ofa vault, in accordance with Section 10, Subsection E, page 45, below.B. Sealin2 Conditions.Vaults. At the approval of the enforcing agency, the top of the annular seal and wellcasing can be below ground surface where traffic or other conditions require. In nocase shall the top of the annular seal be more than 4 feet below ground surface.The top of the annular seal shall contact a suitable, watertight, structurally-soundsubsurface vault, or equivalent feature, that encloses the top of the well casing inaccordance with Section 10, Subsection E, page 45, below. The vault shall extend fromthe top of the annular seal to at least ground surface.1. Temporary Conductor Casing. If "temporary" conductor casing is used during drilling,it shall be removed during the placement of the casing and annular seal materials, asdescribed in Section 9 of the Water Well Standards. If the temporary conductor casing"cannot" be removed, as defined in Section 9 of the Water Well Standards, sealingmaterial shall be placed between the conductor casing and borehole wall, and betweenthe well casing and conductor casing, in accordance with methods described in Section9 of the Water Well Standards. Sealing material shall extend to at least the depthsspecified in Subsection A of this section..2. Permanent Conductor Casing. If a permanent conductor casing is to be installed, themonitoring well borehole diameter shall be at least 4 inches greater than the outsidediameter of the conductor casing. The inner diameter of the permanent conductor-42-
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--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 32 and 33: "8. 2.casing and the borehole wall
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 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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