AUDIENCE: Homeowners/legislators/governmental officials/building contractors/water well contractors

BACKGROUND: Sealing or grouting a well consists of filling the annular space, created during the well construction between the underground geological formations and the casing, with an impervious material. The principal reasons for grouting are (1) protection of the ground water resource from surface and/or subsurface contamination, (2) preservation of the hydraulic characteristics of an artesian aquifer, and (3) sanitary protection of the water supply. In addition, secondary reasons include the protection of casing from corrosive waters, and increased structural integrity of the casing.

According to the 1980 U.S. census, 13 million households - 37 million people, used private wells as their source of drinking water. Another 74 million Americans drank ground water supplied by public water utility wells.

The Michigan Department of Health has identified cases where improper grouting practices or lack of grouting in unconsolidated materials is suspected of causing leakage of contaminants downward along the well casing into lower potable aquifers. In addition. many cases have been documented in Michigan showing that a lack of grouting or improper grouting has contributed to the contamination of bedrock aquifers

Proper grouting of wells, on the other hand, can prevent contamination. In the Gateway Area Development District Water Well Study, the Kentucky Division of Water and the Kentucky Geological Survey report:

"It was noted that the majority of wells which appeared to be properly constructed and had proper wellhead seals did not have a bacterial contamination problem."

ISSUE: Should all water wells be grouted? Should laws and regulations be adopted to this effect?

POSITION: The National Ground Water Association (NGWA) believes that the grouting of water wells is an effective and necessary measure to protect public health and the quality of our ground water supplies.

Requirements for the grouting of all water wells should be an integral part of a state's well construction code. As a follow-up to this, enforcement of the code must be carried out by governmental agencies in an aggressive manner with sufficient funding provided by the state legislature to support this effort.

To protect against contamination by surface or shallow subsurface waters, an annular space of appropriate size should be constructed and grouted to whatever depth is necessary to protect the ground water resource. In determining the grouting requirements of a specific well, consideration must be given to existing surface conditions, especially the location of potential pollution sources, and to subsurface geologic and hydrologic conditions. The surface seal depth may vary from as little as 10 feet to more than 100 feet depending upon conditions.

Subsurface formations that yield water of undesirable quality must be adequately sealed off to prevent contamination of the overlying or underlying waterbearing zones. To accomplish this, an annular space of appropriate size should be constructed and grouted.

Where the grout is to be placed under water or where the annular space to be sealed is not easily accessible from the surface, positive emplacement of grout by tremie, pumping, or pressure is recommended.

For information on grouting techniques, refer to the Manual of Water Well Construction Practices, U.S. Environmental Protection Agency, 1975, and the Michigan Water Well Grouting Manual, Michigan Department of Public Health, 1988.

CONTACT: Chris Reimer, NGWA, 800/ 551-7379

REFERENCE: Kentucky Natural Resources and Environmental Protection Cabinet, Division of Water, and Kentucky Geological Survey, Gateway Area Development District Water Well Study Report, 1988.

McCray, Kevin, "Tapping the Water Market " American Demographics. 9:42, January 1987

Michigan Department of Public Health, Michigan Water Well Grouting Manual, 1988.

U.S. Environmental Protection Agency, Manual of Water Well Construction Practices. 19-5.