Washington Administrative Code › Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508) › Chapter 173-160 - Minimum standards for construction and maintenance of wells › Part ONE - GENERAL REQUIREMENTS FOR WATER WELL CONSTRUCTIO › Section 173-160-201 - What are the casing and liner requirements?

Current through Register Vol. 24-14, July 15, 2024
(1) Proper casing must be installed in all
				water supply wells.
(2) The casing
				shall withstand typical forces which act upon it during and after installation.
				It shall be resistant to the corrosive effects of the surrounding formations,
				earth, and water and shall be impervious to any contaminants
				encountered.
(3) All plastic casing
				or liner pipe used in potable water supply wells must be manufactured to
				conform to National Sanitation Foundation (NSF) Standard 14-84, or the most
				recent revision.
(4) Unless prior
				approval is obtained from the department, well casings and liner pipes must be
				made of either steel or plastic.
(5) Liner pipe must be of sufficient strength
				to withstand breakage or collapse when the well is pumped and meet ASTM potable
				water standards.
(6) When
				installed, liner pipe shall extend or telescope at least two feet into the
				lower end of the well casing. If more than one string of liner pipe is
				installed, each string shall extend or telescope at least eight feet into the
				adjacent larger diameter liner pipe.
(7) Liner pipe may not be permanently fixed
				to a well casing below land surface.
(8) Minimum specifications for steel casing
				and steel liner pipe for water wells are shown in Table 1.
TABLE 1
Minimum Specifications for Steel Casing and Steel Liner
				  Pipe
NOMINAL
SIZE
(inches)
OUTSIDE
DIAMETER
(inches)
WALL
THICKNESS (inches)
WEIGHT
PER FOOT (pounds)
TEST
SECTION
OUTSIDE
DIAMETER
(inches)
1.25
1.660
0.140
2.27
0.500
1.5
1.900
0.145
2.72
0.750
2.0
2.375
0.154
3.65
1.000
2.5
2.875
0.203
5.79
1.500
3.0
3.500
0.216
7.58
2.000
3.5
4.000
0.226
9.11
2.500
4.0
4.500
0.237
10.79
3.000
5.0
5.563
0.258
14.62
3.500
6.0
6.625
0.250
17.02
4.000
8.0
8.625
0.250
22.36
6.000
10
10.750
0.250
28.04
8.000
12
12.750
0.250
33.38
10.000
14
14.000
0.312
45.61
11.000
16
16.000
0.375
57.52
14.000
18
18.000
0.375
70.59
16.000
20
20.000
0.375
78.60
18.000
24
24.000
0.375
94.62
20.000
30
30.000
0.375
118.65
24.000
(9)
				Steel casing larger than thirty inches shall have a minimum wall thickness of
				0.375 inches.
(10) Minimum
				specifications for plastic casing and plastic liner pipe for water wells are
				shown in Table 2.
TABLE 2
Minimum Specifications for Plastic Casing and Plastic Liner
				  Pipe
NOMINAL CASING
DIAMETER
(inches)
MINIMUM
THICKNESS
(inches)
SDR
2.0
0.133
21
2.5
0.137
21
3.0
0.167
21
3.5
0.190
21
4.0
0.214
21
4.5
0.236
21
5.0
0.265
21
6.0
0.316
21
8.0
0.410
21
10
0.511
21
12
0.606
21
(11)
				Steel casing and steel liner: All steel casing and steel liner must be new or,
				in like new condition, and be structurally sound.
(a) Casing or liner that has been exposed to
				a contaminant shall not be used in well construction unless the contamination
				can be entirely removed.
(b) When
				casing or liner lengths are joined together, they must be connected by
				watertight weld or screw coupled joints.
(i)
				Welded joints must be at least as thick as the wall thickness of the well
				casing and be fully penetrating.
(ii) All steel well casing or liner shall
				meet or exceed the minimum American Society for Testing and Materials (ASTM)
				A-53 A or B specification for steel pipe.