Minnesota Administrative Rules

4725.6050 REMEDIAL WATER-SUPPLY WELLS.

Subpart 1.

Additional requirements.

In addition to the general standards in parts 4725.2010 to 4725.3875, and the standards for water-supply wells, in parts 4725.4050 to 4725.5550, a remedial well must:

A.

have spark arresters installed if petroleum products or other flammable or explosive materials are present;

B.

be equipped with a casing vent or collect and treat gases, if toxic or flammable gases are present; and

C.

have connections protected with an air gap or back flow prevention device as specified in parts 4715.2010 to 4715.2170, if the well discharges to a sewer or surface water.

Subp. 2.

Exemptions.

A remedial well is exempt from:

A.

the distance from contamination source requirements in parts 4725.4350, subpart 1, and 4725.4450;

B.

the minimum protective depth requirements in part 4725.4550;

C.

the requirement in part 4725.2250, subpart 11, to extend the casing 12 inches above the established ground surface if the remedial well is constructed according to part 4725.6850 for at-grade construction;

D.

the requirement in part 4725.4250, subpart 5, to extend the casing 20 feet below the static water level if the well screen or open hole intersects the water table, the casing terminates no more than ten feet above the static water level, and all casing installed in limestone or dolomite is grouted with neat-cement grout or cement-sand grout;

E.

the venting requirements in part 4725.5450, except as provided in subpart 1, item B; and

F.

the disinfection requirements in part 4725.5550 where disinfection will interfere with water quality analysis or create dangerous reactions with contaminants.

Subp. 3.

Screen or open hole across an unconsolidated formation and bedrock contact.

A remedial well that is constructed to remove contaminants from the water surface by placing a screen or open hole across the contact of an unconsolidated formation and bedrock is exempt from the requirements of part 4725.2020, subpart 1, if the screen or open hole:

A.

intersects the water surface of an unconfined aquifer;

B.

does not penetrate a confining layer; and

C.

does not extend more than 20 feet into bedrock.

Subp. 4.

Stainless steel casing.

A remedial well may be constructed with stainless steel casing meeting ASTM Standard A312/312M-04b, having at least ANSI Schedule 5 for welded joints, and ANSI Schedule 40 for threaded joints.

Statutory Authority:

MS s 103I.101; 103I.111; 103I.205; 103I.221; 103I.301; 103I.401; 103I.451; 103I.501; 103I.525; 103I.531; 103I.535; 103I.541; 103I.621; 144.05; 144.12; 144.383; 157.04; 157.08; 157.09; 157.13

History:

17 SR 2773; 33 SR 211

Published Electronically:

September 2, 2008