S.D. Admin. R. tit. 74, art. 74:02, ch. 74:02:04, app H

Current through Register Vol. 51, page 67, December 16, 2024

Appendix H - Recommended procedure for chlorine disinfection of water wells

(See § 74:02:04:58.01)

RECOMMENDED PROCEDURE FOR CHLORINE DISINFECTION OF WATER WELLS *

Introduction

A water well should be thoroughly cleaned and disinfected with a strong chlorine solution after:

1. ORIGINAL CONSTRUCTION	4. A PERIOD OF NONUSE
2. ANY REPAIR OR MAINTENANCE	5. TWO OR MORE "UNSAFE" WATER
3. FLOODING	BATERIOLOGICAL SAMPLES
ARE TRACED TO THE WELL

Adequate chlorine requires a certain chlorine dosage for a minimum contact time - 100 parts per million for 2 hours, 50 parts per million for 8 hours, or 25 parts per million for 24 hours.

Chlorine for disinfection of water wells can be either 5.25% sodium hypochlorite solution of 65% calcium hypochlorite powder. A 5.25% hypochlorite solution is common household chlorine bleach such as "Hilex," "Chlorox," or "Purex" available at grocery stores and supermarkets. The 65% calcium hypochlorite powder is available from chemical supply houses and is known commercially as "HTH," "Perchloron," or "Pittchlor."

Recommended Procedure

1 Determine the chlorine dosage for the desired contact time from the following tables:

AMOUNT OF CHLORINE NECESSARY PER 10 FEET OF WATER IN WELL

5.25% Sodium Hypochlorite (Bleach)

Inside Diameter
of Well	100 ppm*	50 ppm*	25 ppm*
Casing	for 2 hrs	for 8 hrs	for 24 hrs
1 1/4 inches	1/8 fl.oz.	----------	----------
2 inches	1/2 fl.oz.	1/4 fl.oz.	1/8 fl.oz.
3 inches	1 fl.oz.	1/2 fl.oz.	1/4 fl.oz.
4 inches	1 1/2 fl.oz.	3/4 fl.oz.	3/8 fl.oz.
6 inches	4 fl.oz.	2 fl.oz.	1 fl.oz.
8 inches	7 fl.oz.	3 1/2 fl.oz.	1 3/4 fl.oz.
10 inches	10 fl.oz.	5 fl.oz.	2 fl.oz.
12 inches	2 cups	1 cup	1/2 cup
18 inches	4 1/2 cups	2 1/4 cups	1 1/8 cups
24 inches	7 1/2 cups	3 3/4 cups	1 7/8 cups
36 inches	17 1/2 cups	8 3/4 cups	4 3/8 cups

65% Calcium Hypochlorite

100 ppm*	50 ppm*	25 ppm*
for 2 hrs	for 8 hrs	for 24 hrs
-----------	-----------	-----------
-----------	-----------	-----------
-----------	-----------	-----------
-----------	-----------	-----------
1/4 oz.	1/8 oz.	1/16 oz.
1/2 oz.	1/4 oz.	1/8 oz.
3/4 oz.	3/8 oz.	1/16 oz.
1 oz.	1/2 oz.	1/4 oz.
1 1/2 oz.	1 1/4 oz.	5/7 oz.
4 1/2 oz.	2 1/4 oz.	1 1/8 oz.
10 oz.	5 oz.	1 1/2 oz.
* ppm = parts per million	1 heaping tablespoon of 65%
8 fluid ounces = 1 cup	chlorine powder = 1/2 oz

2. Prepare a chlorine solution, lift well pump, and pour the chlorine solution into the well.

3. Lower the pump and operate until a chlorine odor is noticed at all discharge points.

4. Leave the chlorine and water solution in the well for the recommended contact time. Donot use the water.

5. At the end of the contact time, pump the well to waste until the chlorine odor cannot be detected. DO NOT ALLOW CHLORINATED WATER TO ENTER A RIVER, LAKE, OR STREAM.

6. Pump the well for a considerable period of time, collect a bacteriological water sample, and submit it for testing.

S.D. Admin. R. tit. 74, art. 74:02, ch. 74:02:04, app H

18 SDR 224, effective 7/16/1992.

AWWA A 100-90, "AWWA Standard for Water Wells," January 29, 1990. Published by American Water Works Association, 666 West Quincy, Denver, CO 80235