Purpose: To revise the casing wall thickness for 6 and 8 inch diameter pipe to reflect the industry standard for well construction.

Citation of Existing Rules Affected by this Order: Amending WAC 173-160-201 (Table 1).

Statutory Authority for Adoption: Chapter 18.104 RCW.

Under RCW 34.05.350 the agency for good cause finds that immediate adoption, amendment, or repeal of a rule is necessary for the preservation of the public health, safety, or general welfare, and that observing the time requirements of notice and opportunity to comment upon adoption of a permanent rule would be contrary to the public interest.

Reasons for this Finding: The pipe wall thickness specifications for 6 - 16 inch diameter casings cited in Table 1, WAC 173-160-201 exceed the industry standard for well casing and are in error. This emergency rule will correct the error while maintaining a high level of public protection.

Number of Sections Adopted in Order to Comply with Federal Statute: New 0, amended 0, repealed 0; Federal Rules or Standards: New 0, amended 0, repealed 0; or Recently Enacted State Statutes: New 0, amended 0, repealed 0.

Number of Sections Adopted at Request of a Nongovernmental Entity: New 0, amended 0, repealed 0.

Number of Sections Adopted on the Agency's Own Initiative: New 0, amended 1, repealed 0.

Number of Sections Adopted in Order to Clarify, Streamline, or Reform Agency Procedures: New 0, amended 0, repealed 0.

Number of Sections Adopted Using Negotiated Rule Making: New 0, amended 0, repealed 0; Pilot Rule Making: New 0, amended 0, repealed 0; or Other Alternative Rule Making: New 0, amended 0, repealed 0.

Effective Date of Rule: Immediately.

April 26, 1998

Tom Fitzsimmons

Director

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.

(3) All plastic casing for use 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, materials for well casings must be either steel casing as shown in Table 1 or plastic casing as shown in Table 2.

(5) Minimum specifications for steel casing and pipe for water wells are shown in Table 1.

(6) Steel casing larger than twenty inches shall have a minimum wall thickness of 0.375 inches.

TABLE 1

Minimum Specifications for Steel Casing and Pipe

steel casing

(7) All steel casing materials must be new or, in like new condition, and be structurally sound.

(a) Casing that has been exposed to a contaminant shall not be used in well construction unless the contamination can be entirely removed.

(b) When casing 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 shall meet or exceed the minimum American Society for Testing and Materials (ASTM) A-53 A or B specification for steel pipe.

plastic casing

(8) Plastic, fiberglass, PVC, SR, ABS, or other type of nonmetallic well casing must be manufactured and installed to conform with ANSI/ASTM F 480-81, Standard Dimension Ratio (SDR) 21 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; 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.

(d) All plastic casing must be new or, in like new condition and clearly marked by the manufacturer showing nominal size, 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 that has been exposed to a contaminant shall not be used in well construction unless the construction can be entirely removed.

(f) Plastic casing 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.

(g) Table 2 is the manufacturer's recommendations for specifications of plastic casing.

TABLE 2

Minimum Specifications for Plastic Casing

liner pipe

(9) Liner pipe must consist of steel, in new or like new condition, free of pits or breaks; or polyvinyl chloride (PVC), CPVC, type 1120, with SDR 21 (Class 200) or greater wall thickness. All PVC must be clearly marked to identify the type, class, and SDR.

(a) Liner pipe must be of sufficient strength to withstand breakage or collapse when the well is pumped and meet ASTM potable water standards.

(b) 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.

(c) Liner pipe may not be permanently fixed to a well casing below land surface.

concrete curbing

(10) 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.

(11) The curbing shall be at least six inches thick and free of voids. The walls shall be poured in one continuous operation.

(12) 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 and RCW 43.21A.080. 98-08-032 (Order 97-08), § 173-160-201, filed 3/23/98, effective 4/23/98.]

Reviser's note: The bracketed material preceding the section above was supplied by the code reviser's office.

Reviser's note: The typographical error in the above section occurred in the copy filed by the agency and appears in the Register pursuant to the requirements of RCW 34.08.040.