OAR 690-210-0140
Sealing of Water Supply Wells in Unconsolidated Formations with Significant Clay Beds

Water supply wells drilled into water-bearing intervals overlain by unconsolidated deposits of clay, or sand and gravel in which significant interbeds of clay are present, shall have a watertight, nonperforated, permanent well casing extending at least five feet into the clay interval overlying the water-bearing zone. In all cases, an upper oversize drillhole, at least four inches greater in diameter than the nominal diameter of the permanent well casing shall be constructed to this same depth. In the event that the subsurface materials penetrated by the upper drillhole cave, or tend to cave, an outer, temporary surface casing shall be used to case out caving materials throughout the construction of the oversize drillhole. If the clay interval is 13 feet or less below land surface, the watertight, nonperforated well casing and the upper, oversize drillhole shall extend to a minimum depth of 18 feet below land surface. If necessary to complete the well, the single, permanent well casing may be extended below the required sealing depth prior to sealing the well with grout. If preferred, a smaller diameter casing, liner, or well screen may be installed. The annular space between the permanent well casing and the upper, oversize drillhole shall be completely filled with grout in accordance with OAR 690-210-0310 (Cement Grout) through 690-210-0360 (Movement of Casing after Cement Grouting) after the permanent well casing is set into final position. The temporary surface casing shall be removed from the well as the annular space is filled. (See Figure 210-3).
[ED. NOTE: Figures referenced are available from the agency.]

Source: Rule 690-210-0140 — Sealing of Water Supply Wells in Unconsolidated Formations with Significant Clay Beds, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=690-210-0140.

690–210–0005
Standards Apply to all Methods of Well Construction 690–210–0030
Placement of Water Supply Wells 690–210–0060
Explosives 690–210–0065
Hydrofracturing 690–210–0070
Injection Wells 690–210–0100
Mineralized or Contaminated Groundwater 690–210–0130
Sealing of Wells in Unconsolidated Formations Without Significant Clay Beds 690–210–0140
Sealing of Water Supply Wells in Unconsolidated Formations with Significant Clay Beds 690–210–0150
Sealing of Water Supply Wells in Consolidated Formations 690–210–0155
Additional Standards for Artesian Water Supply Wells 690–210–0160
Additional Standards for Filter Pack Wells with Surface Casing 690–210–0170
Additional Standards for Filter Pack Wells without Surface Casing 690–210–0180
Additional Standards for Driven or Jetted Wells 690–210–0190
Steel Casing 690–210–0200
Steel Casing Joints 690–210–0210
Plastic Casing 690–210–0220
Plastic Casing Joints 690–210–0230
Inner Casing 690–210–0240
Casing Shall be Centered 690–210–0250
Top Terminal Height 690–210–0260
Openings in the Casing 690–210–0270
Pitless Well Adapters and Units 690–210–0280
Access Ports, Dedicated Measuring Tubes and Airlines 690–210–0290
Liner Pipe 690–210–0300
Drill Cuttings or Chips 690–210–0310
Cement Grout 690–210–0315
Concrete 690–210–0320
Methods of Placement of Cement Grout or Concrete 690–210–0330
Unhydrated Bentonite 690–210–0340
Method of Placement of Unhydrated Bentonite 690–210–0350
Resumption of Construction Following Placement of Cement Grout 690–210–0360
Movement of Casing after Cement Grouting 690–210–0370
Well Test 690–210–0380
Disinfection of a Well 690–210–0390
Completion of Wells 690–210–0400
Construction of Dug Wells 690–210–0410
Buried Slab Construction 690–210–0420
Surface Curbing
Last Updated

Jun. 8, 2021

Rule 690-210-0140’s source at or​.us