WAC 173-160-201
What are the casing and liner
requirements? (1) Proper casing must be installed in all
water supply wells.
(2) The casing shall withstand normal 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.
(9) Minimum specifications for plastic casing and plastic
liner pipe for water wells are shown in Table 2.
(10) Steel casing larger than twenty inches shall have a
minimum wall thickness of 0.375 inches.
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 |
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 |
STEEL CASING AND STEEL LINER
(11) 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.
PLASTIC CASING AND PLASTIC LINER
(12) Plastic, fiberglass, PVC, SR, ABS, CPVC or other
type of nonmetallic well casing or liner must be manufactured
and installed to conform with ANSI/ASTM F 480-81, or the most
recent revision.
(a) SDR is calculated by dividing the outside diameter of
the pipe by the wall thickness.
(b) SDR 21 is the minimum requirement (Class 200); higher
pressure rated pipe may be used.
(c) All plastic casing must be installed only in an
oversized drill hole without driving. The oversized hole must
be a diameter of at least 4 inches larger than the outside
diameter of the plastic casing or coupling hubs, whichever is
larger. Plastic casing and liner must be of sufficient
strength to withstand breakage or collapse when installed and
while the well is pumped. Plastic casing and liner must meet
ASTM potable water standards.
(d) All plastic casing or liner must be new or, in like
new condition and clearly marked by the manufacturer showing
nominal size, class, type of plastic material, SDR, ASTM
designation, and have a National Sanitation Foundation (NSF)
seal of approval for use in potable water supplies.
(e) Casing or liner that has been exposed to a
contaminant shall not be used in well construction unless the
contaminant is entirely removed.
(f) Plastic casing or liner joints must be watertight.
(i) Either "bell" type, threaded joints, or coupling hubs
are approved.
(ii) Hub couplings must be of materials meeting the
specifications for plastic casings as stipulated in subsection
(2) of this section.
(iii) If joints are secured with solvent cement, it must
be done in accordance with manufacturer's directions.
CONCRETE CURBING
(13) The concrete used to make curbing must consist of
clean, hard and durable aggregate with not less than five
sacks (ninety-four pounds per sack) of portland cement per
cubic yard of concrete.
(a) The maximum diameter of aggregate particles may not
exceed 1 1/2 inches, but in any case may not exceed 1/5 the
minimum width of the casing thickness.
(b) The ratio of coarse aggregate to fine aggregate
(passing No. 4 U.S. Standard Sieve) must be approximately 1
1/2 to 1 by volume, but in any case, may not exceed 2 to 1 nor
be less than 1 to 2.
(14) The curbing shall be at least six inches thick and
free of voids. The walls shall be poured in one continuous
operation.
(15) When concrete tile is used to line a well, the
combined total wall thickness and seal shall be a minimum of
six inches.
[Statutory Authority: Chapter 18.104 RCW. 06-23-121 (Order
06-08), § 173-160-201, filed 11/21/06, effective 12/22/06;
98-18-104 (Order 98-17), § 173-160-201, filed 9/2/98,
effective 10/3/98. Statutory Authority: Chapter 18.104 RCW
and RCW 43.21A.080. 98-08-032 (Order 97-08), § 173-160-201,
filed 3/23/98, effective 4/23/98.]